638939520 has 96 divisors (see below), whose sum is σ = 2206357920. Its totient is φ = 170382336.

The previous prime is 638939519. The next prime is 638939551. The reversal of 638939520 is 25939836.

638939520 is a `hidden beast` number, since 6 + 38 + 93 + 9 + 520 = 666.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 49704 + ... + 61223.

It is an arithmetic number, because the mean of its divisors is an integer number (22982895).

Almost surely, 2^638939520 is an apocalyptic number.

638939520 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

638939520 is an abundant number, since it is smaller than the sum of its proper divisors (1567418400).

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

638939520 is a wasteful number, since it uses less digits than its factorization.

638939520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110952 (or 110937 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 45.

The square root of 638939520 is about 25277.2530153100. The cubic root of 638939520 is about 861.2976264298.

The spelling of 638939520 in words is "six hundred thirty-eight million, nine hundred thirty-nine thousand, five hundred twenty".