166556661 has 8 divisors (see below), whose sum is σ = 222620160. Its totient is φ = 110765472.

The previous prime is 166556653. The next prime is 166556671. The reversal of 166556661 is 166655661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 166556661 - 2³ = 166556653 is a prime.

It is a super-2 number, since 2×166556661² = 55482242646937842, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166556671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 66645 + ... + 69098.

It is an arithmetic number, because the mean of its divisors is an integer number (27827520).

Almost surely, 2^166556661 is an apocalyptic number.

It is an amenable number.

166556661 is a deficient number, since it is larger than the sum of its proper divisors (56063499).

166556661 is a wasteful number, since it uses less digits than its factorization.

166556661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136155.

The product of its digits is 194400, while the sum is 42.

The square root of 166556661 is about 12905.6832829572. The cubic root of 166556661 is about 550.2001045983.

The spelling of 166556661 in words is "one hundred sixty-six million, five hundred fifty-six thousand, six hundred sixty-one".