639981560 has 32 divisors (see below), whose sum is σ = 1515747600. Its totient is φ = 242519040.

The previous prime is 639981497. The next prime is 639981571. The reversal of 639981560 is 65189936.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 420281 + ... + 421800.

Almost surely, 2^639981560 is an apocalyptic number.

It is an amenable number.

639981560 is an abundant number, since it is smaller than the sum of its proper divisors (875766040).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

639981560 is a wasteful number, since it uses less digits than its factorization.

639981560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 842111 (or 842107 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 47.

The square root of 639981560 is about 25297.8568262215. The cubic root of 639981560 is about 861.7655993133.

The spelling of 639981560 in words is "six hundred thirty-nine million, nine hundred eighty-one thousand, five hundred sixty".