Compare 18 vs 31

Typecomposite numberprime
Unique factors21
Total factors31
Prime factorization21 × 32311
Prime factorization2 × 3 × 331
Divisors count62
Divisors1, 2, 3, 6, 9, 181, 31
Number of properties018
Centered decagonal primes 2nd
Centered triangular primes 2nd
Chen primes 11th
Class 1+ primes 8th
Emirps 3rd
Euclid primes 4th
Happy primes 5th
Lucky primes 4th
Mersenne primes 3rd
Multiplicative primes 7th
Pierpont primes of the 2nd kind 8th
Primes 11th
Right-truncatable primes 7th
Sexy primes (1st member) 7th
Sexy prime triplets (1st member) 5th
Solinas primes 10th
Super primes 5th
Twin primes (2nd member) 5th
Roman numberalsXVIIIXXXI
Base 2100102111112
Base 3200310113
Base 410241334
Base 53351115
Base 6306516
Base 7247437
Base 8228378
Base 9209349
Base 1018103110
Base 1117112911
Base 1216122712
Base 1315132513
Base 1414142314
Base 1513152115
Base 1612161f16
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