639031386826 has 72 divisors (see below), whose sum is σ = 1210139049708. Its totient is φ = 251472614400.

The previous prime is 639031386821. The next prime is 639031386841. The reversal of 639031386826 is 628683130936.

It can be written as a sum of positive squares in 6 ways, for example, as 168982655625 + 470048731201 = 411075^2 + 685601^2 .

It is a super-2 number, since 2×639031386826² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (639031386821) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2686456 + ... + 2914636.

Almost surely, 2^639031386826 is an apocalyptic number.

639031386826 is a deficient number, since it is larger than the sum of its proper divisors (571107662882).

639031386826 is a wasteful number, since it uses less digits than its factorization.

639031386826 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228296 (or 228248 counting only the distinct ones).

The product of its (nonzero) digits is 6718464, while the sum is 55.

The spelling of 639031386826 in words is "six hundred thirty-nine billion, thirty-one million, three hundred eighty-six thousand, eight hundred twenty-six".