166877981 has 2 divisors, whose sum is σ = 166877982. Its totient is φ = 166877980.

The previous prime is 166877947. The next prime is 166877989. The reversal of 166877981 is 189778661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 123765625 + 43112356 = 11125^2 + 6566^2 .

It is a cyclic number.

It is not a de Polignac number, because 166877981 - 2⁶ = 166877917 is a prime.

It is a super-2 number, since 2×166877981² = 55696521085272722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166877989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83438990 + 83438991.

It is an arithmetic number, because the mean of its divisors is an integer number (83438991).

Almost surely, 2^166877981 is an apocalyptic number.

It is an amenable number.

166877981 is a deficient number, since it is larger than the sum of its proper divisors (1).

166877981 is an equidigital number, since it uses as much as digits as its factorization.

166877981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1016064, while the sum is 53.

The square root of 166877981 is about 12918.1260637911. The cubic root of 166877981 is about 550.5536914411.

The spelling of 166877981 in words is "one hundred sixty-six million, eight hundred seventy-seven thousand, nine hundred eighty-one".