166655681 has 4 divisors (see below), whose sum is σ = 166828992. Its totient is φ = 166482372.

The previous prime is 166655653. The next prime is 166655689. The reversal of 166655681 is 186556661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 166655681 - 2¹⁸ = 166393537 is a prime.

It is a super-2 number, since 2×166655681² = 55548232019147522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166655689) 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 in 3 ways as a sum of consecutive naturals, for example, 85205 + ... + 87138.

It is an arithmetic number, because the mean of its divisors is an integer number (41707248).

Almost surely, 2^166655681 is an apocalyptic number.

It is an amenable number.

166655681 is a deficient number, since it is larger than the sum of its proper divisors (173311).

166655681 is an equidigital number, since it uses as much as digits as its factorization.

166655681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173310.

The product of its digits is 259200, while the sum is 44.

The square root of 166655681 is about 12909.5190073062. The cubic root of 166655681 is about 550.3091165927.

The spelling of 166655681 in words is "one hundred sixty-six million, six hundred fifty-five thousand, six hundred eighty-one".