638953920 has 448 divisors, whose sum is σ = 2519354880. Its totient is φ = 153031680.

The previous prime is 638953919. The next prime is 638953943. The reversal of 638953920 is 29359836.

638953920 is a `hidden beast` number, since 638 + 9 + 5 + 3 + 9 + 2 + 0 = 666.

It is a super-2 number, since 2×638953920² = 816524223766732800, which contains 22 as substring.

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 polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 7698199 + ... + 7698281.

It is an arithmetic number, because the mean of its divisors is an integer number (5623560).

Almost surely, 2^638953920 is an apocalyptic number.

638953920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638953920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1259677440).

638953920 is an abundant number, since it is smaller than the sum of its proper divisors (1880400960).

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

638953920 is an equidigital number, since it uses as much as digits as its factorization.

638953920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132 (or 104 counting only the distinct ones).

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

The square root of 638953920 is about 25277.5378547832. The cubic root of 638953920 is about 861.3040968349.

The spelling of 638953920 in words is "six hundred thirty-eight million, nine hundred fifty-three thousand, nine hundred twenty".