639090657 has 12 divisors (see below), whose sum is σ = 945646884. Its totient is φ = 415668480.

The previous prime is 639090649. The next prime is 639090671. The reversal of 639090657 is 756090936.

639090657 is a `hidden beast` number, since 639 + 0 + 9 + 0 + 6 + 5 + 7 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 340181136 + 298909521 = 18444^2 + 17289^2 .

It is not a de Polignac number, because 639090657 - 2³ = 639090649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (639095657) 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, 865608 + ... + 866345.

It is an arithmetic number, because the mean of its divisors is an integer number (78803907).

Almost surely, 2^639090657 is an apocalyptic number.

It is an amenable number.

639090657 is a deficient number, since it is larger than the sum of its proper divisors (306556227).

639090657 is a wasteful number, since it uses less digits than its factorization.

639090657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1732000 (or 1731997 counting only the distinct ones).

The product of its (nonzero) digits is 306180, while the sum is 45.

The square root of 639090657 is about 25280.2424236794. The cubic root of 639090657 is about 861.3655325318.

The spelling of 639090657 in words is "six hundred thirty-nine million, ninety thousand, six hundred fifty-seven".