638509891406 has 16 divisors (see below), whose sum is σ = 980087222400. Its totient is φ = 311814889848.

The previous prime is 638509891387. The next prime is 638509891447. The reversal of 638509891406 is 604198905836.

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, 1659305 + ... + 2007563.

It is an arithmetic number, because the mean of its divisors is an integer number (61255451400).

Almost surely, 2^638509891406 is an apocalyptic number.

638509891406 is a deficient number, since it is larger than the sum of its proper divisors (341577330994).

638509891406 is a wasteful number, since it uses less digits than its factorization.

638509891406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 369623.

The product of its (nonzero) digits is 11197440, while the sum is 59.

The spelling of 638509891406 in words is "six hundred thirty-eight billion, five hundred nine million, eight hundred ninety-one thousand, four hundred six".