166556231 has 4 divisors (see below), whose sum is σ = 166852632. Its totient is φ = 166259832.

The previous prime is 166556213. The next prime is 166556239. The reversal of 166556231 is 132655661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 132655661 = 53 ⋅2502937.

It is a cyclic number.

It is not a de Polignac number, because 166556231 - 2⁶ = 166556167 is a prime.

It is a super-2 number, since 2×166556231² = 55481956169850722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 166556191 and 166556200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166556239) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 147356 + ... + 148481.

It is an arithmetic number, because the mean of its divisors is an integer number (41713158).

Almost surely, 2^166556231 is an apocalyptic number.

166556231 is a deficient number, since it is larger than the sum of its proper divisors (296401).

166556231 is an equidigital number, since it uses as much as digits as its factorization.

166556231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296400.

The product of its digits is 32400, while the sum is 35.

The square root of 166556231 is about 12905.6666236193. Note that the first 4 decimals coincide. The cubic root of 166556231 is about 550.1996311133.

The spelling of 166556231 in words is "one hundred sixty-six million, five hundred fifty-six thousand, two hundred thirty-one".