666616926921 has 24 divisors (see below), whose sum is σ = 977644342752. Its totient is φ = 403731504000.

The previous prime is 666616926887. The next prime is 666616926967. The reversal of 666616926921 is 129629616666.

It is not a de Polignac number, because 666616926921 - 2⁷ = 666616926793 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666616926221) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 106096 + ... + 1159521.

It is an arithmetic number, because the mean of its divisors is an integer number (40735180948).

Almost surely, 2^666616926921 is an apocalyptic number.

It is an amenable number.

666616926921 is a deficient number, since it is larger than the sum of its proper divisors (311027415831).

666616926921 is a wasteful number, since it uses less digits than its factorization.

666616926921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1267093 (or 1267082 counting only the distinct ones).

The product of its digits is 15116544, while the sum is 60.

The spelling of 666616926921 in words is "six hundred sixty-six billion, six hundred sixteen million, nine hundred twenty-six thousand, nine hundred twenty-one".