666623957 has 12 divisors (see below), whose sum is σ = 694376460. Its totient is φ = 639213120.

The previous prime is 666623953. The next prime is 666623959. The reversal of 666623957 is 759326666.

It can be written as a sum of positive squares in 2 ways, for example, as 123454321 + 543169636 = 11111^2 + 23306^2 .

It is not a de Polignac number, because 666623957 - 2² = 666623953 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666623953) 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, 2129633 + ... + 2129945.

It is an arithmetic number, because the mean of its divisors is an integer number (57864705).

Almost surely, 2^666623957 is an apocalyptic number.

It is an amenable number.

666623957 is a deficient number, since it is larger than the sum of its proper divisors (27752503).

666623957 is an equidigital number, since it uses as much as digits as its factorization.

666623957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 884 (or 613 counting only the distinct ones).

The product of its digits is 2449440, while the sum is 50.

The square root of 666623957 is about 25819.0618923306. The cubic root of 666623957 is about 873.5618091727.

The spelling of 666623957 in words is "six hundred sixty-six million, six hundred twenty-three thousand, nine hundred fifty-seven".