639668977589 has 4 divisors (see below), whose sum is σ = 677296564524. Its totient is φ = 602041390656.

The previous prime is 639668977573. The next prime is 639668977631. The reversal of 639668977589 is 985779866936.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 470344957489 + 169324020100 = 685817^2 + 411490^2 .

It is a cyclic number.

It is not a de Polignac number, because 639668977589 - 2⁴ = 639668977573 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639668977559) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18813793442 + ... + 18813793475.

It is an arithmetic number, because the mean of its divisors is an integer number (169324141131).

Almost surely, 2^639668977589 is an apocalyptic number.

It is an amenable number.

639668977589 is a deficient number, since it is larger than the sum of its proper divisors (37627586935).

639668977589 is a wasteful number, since it uses less digits than its factorization.

639668977589 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37627586934.

The product of its digits is 7407106560, while the sum is 83.

The spelling of 639668977589 in words is "six hundred thirty-nine billion, six hundred sixty-eight million, nine hundred seventy-seven thousand, five hundred eighty-nine".