639777890655 has 12 divisors (see below), whose sum is σ = 1108948343880. Its totient is φ = 341214874992.

The previous prime is 639777890597. The next prime is 639777890729. The reversal of 639777890655 is 556098777936.

It is not a de Polignac number, because 639777890655 - 2⁸ = 639777890399 is a prime.

It is a super-2 number, since 2×639777890655² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7108643185 + ... + 7108643274.

It is an arithmetic number, because the mean of its divisors is an integer number (92412361990).

Almost surely, 2^639777890655 is an apocalyptic number.

639777890655 is a deficient number, since it is larger than the sum of its proper divisors (469170453225).

639777890655 is a wasteful number, since it uses less digits than its factorization.

639777890655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14217286470 (or 14217286467 counting only the distinct ones).

The product of its (nonzero) digits is 600112800, while the sum is 72.

The spelling of 639777890655 in words is "six hundred thirty-nine billion, seven hundred seventy-seven million, eight hundred ninety thousand, six hundred fifty-five".