666566651 has 12 divisors (see below), whose sum is σ = 709206840. Its totient is φ = 626361600.

The previous prime is 666566623. The next prime is 666566669. The reversal of 666566651 is 156665666.

It is a de Polignac number, because none of the positive numbers 2^k-666566651 is a prime.

It is a super-2 number, since 2×666566651² = 888622200450711602, 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 = 666566596 and 666566605.

It is not an unprimeable number, because it can be changed into a prime (666565651) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 232376 + ... + 235226.

It is an arithmetic number, because the mean of its divisors is an integer number (59100570).

Almost surely, 2^666566651 is an apocalyptic number.

666566651 is a deficient number, since it is larger than the sum of its proper divisors (42640189).

666566651 is a wasteful number, since it uses less digits than its factorization.

666566651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3694 (or 3677 counting only the distinct ones).

The product of its digits is 1166400, while the sum is 47.

The square root of 666566651 is about 25817.9521070127. The cubic root of 666566651 is about 873.5367766852.

The spelling of 666566651 in words is "six hundred sixty-six million, five hundred sixty-six thousand, six hundred fifty-one".