9,192,631,770
9,192,631,770 is the number of caesium-133 oscillations that define one second.
- Even
- Composite
Where 9,192,631,770 fits
Why 9,192,631,770 is special
It is the number that replaced the Earth. Until 1967 a second was a fraction of a day, so time was tied to a planet whose rotation is neither constant nor perfectly predictable. The figure is not round because it was chosen to match the astronomical second then in use as closely as possible — the definition changed while the length of a second deliberately did not.
9,192,631,770 is part of
Factors & digit properties
- Divisors (144)
- 1, 2, 3, 5, 6, 7, 9, 10, 14, 15, 18, 21, 30, 35, 42, 45, 47, 49, 63, 70, 90, 94, 98, 105, 126, 141, 147, 210, 235, 245, 282, 294, 315, 329, 423, 441, 470, 490, 630, 658, 705, 735, 846, 882, 987, 1410, 1470, 1645, 1974, 2115, 2205, 2303, 2961, 3290, 4230, 4410, 4606, 4935, 5922, 6909, 9870, 11515, 13818, 14805, 20727, 23030, 29610, 34545, 41454, 44351, 69090, 88702, 103635, 133053, 207270, 221755, 266106, 310457, 399159, 443510, 620914, 665265, 798318, 931371, 1330530, 1552285, 1862742, 1995795, 2084497, 2173199, 2794113, 3104570, 3991590, 4168994, 4346398, 4656855, 5588226, 6253491, 6519597, 9313710, 10422485, 10865995, 12506982, 13039194, 13970565, 14591479, 18760473, 19558791, 20844970, 21731990, 27941130, 29182958, 31267455, 32597985, 37520946, 39117582, 43774437, 62534910, 65195970, 72957395, 87548874, 93802365, 97793955, 102140353, 131323311, 145914790, 187604730, 195587910, 204280706, 218872185, 262646622, 306421059, 437744370, 510701765, 612842118, 656616555, 919263177, 1021403530, 1313233110, 1532105295, 1838526354, 3064210590, 4596315885, 9192631770
- Prime factorisation
- 2 × 3^2 × 5 × 7^2 × 47 × 44351
- Digit sum
- 45
- Digital root
- 9
Representations
- Decimal
- 9192631770
- Scientific notation
- 9.193 × 10^9
Roman numerals
Roman numerals as modelled here goes up to 3,999.
Binary
Binary (base 2) as modelled here goes up to 1,000,000,000.
Octal
Octal (base 8) as modelled here goes up to 1,000,000,000.
Hexadecimal
Hexadecimal (base 16) as modelled here goes up to 1,000,000,000.
Other mathematical patterns
- Abundant number
- Harshad (Niven) number
Related numbers & connections
9192631770 appears in Numbers in physics, the topic covering numbers that carry a documented physics fact.
Numbers Around Us
- appears inPhysics
why?
Strength 0.50, confidence "high".
Science
The caesium-133 hyperfine transition frequency that defines the second is 9,192,631,770 hertz (worldwide, SI, since 1967). Exact by definition: the second is that many oscillations, so the figure cannot be improved by a better measurement. The 1967 redefinition was chosen to match the astronomical second then in use as closely as possible, which is why the number is not round.
DocumentedScienceGeography: worldwide, SI, since 1967
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 15 July 2026