638840490 has 32 divisors (see below), whose sum is σ = 1537107840. Its totient is φ = 169925184.

The previous prime is 638840443. The next prime is 638840509. The reversal of 638840490 is 94048836.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14910 + ... + 38729.

It is an arithmetic number, because the mean of its divisors is an integer number (48034620).

Almost surely, 2^638840490 is an apocalyptic number.

638840490 is an abundant number, since it is smaller than the sum of its proper divisors (898267350).

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

638840490 is a wasteful number, since it uses less digits than its factorization.

638840490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54046.

The product of its (nonzero) digits is 165888, while the sum is 42.

The square root of 638840490 is about 25275.2940635712. The cubic root of 638840490 is about 861.2531262811.

The spelling of 638840490 in words is "six hundred thirty-eight million, eight hundred forty thousand, four hundred ninety".