166556431 has 2 divisors, whose sum is σ = 166556432. Its totient is φ = 166556430.

The previous prime is 166556419. The next prime is 166556513. The reversal of 166556431 is 134655661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 166556431 - 2⁵ = 166556399 is a prime.

It is a super-2 number, since 2×166556431² = 55482089414915522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161556431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83278215 + 83278216.

It is an arithmetic number, because the mean of its divisors is an integer number (83278216).

Almost surely, 2^166556431 is an apocalyptic number.

166556431 is a deficient number, since it is larger than the sum of its proper divisors (1).

166556431 is an equidigital number, since it uses as much as digits as its factorization.

166556431 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64800, while the sum is 37.

The square root of 166556431 is about 12905.6743721512. The cubic root of 166556431 is about 550.1998513390.

The spelling of 166556431 in words is "one hundred sixty-six million, five hundred fifty-six thousand, four hundred thirty-one".