18139531 has 2 divisors, whose sum is σ = 18139532. Its totient is φ = 18139530.

The previous prime is 18139523. The next prime is 18139543. The reversal of 18139531 is 13593181.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18139531 - 2³ = 18139523 is a prime.

It is a super-2 number, since 2×18139531² = 658085169799922, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 18139493 and 18139502.

It is not a weakly prime, because it can be changed into another prime (18139501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9069765 + 9069766.

It is an arithmetic number, because the mean of its divisors is an integer number (9069766).

Almost surely, 2^18139531 is an apocalyptic number.

18139531 is a deficient number, since it is larger than the sum of its proper divisors (1).

18139531 is an equidigital number, since it uses as much as digits as its factorization.

18139531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3240, while the sum is 31.

The square root of 18139531 is about 4259.0528289750. The cubic root of 18139531 is about 262.7495724694.

The spelling of 18139531 in words is "eighteen million, one hundred thirty-nine thousand, five hundred thirty-one".