639457920 has 192 divisors, whose sum is σ = 2324743200. Its totient is φ = 161519616.

The previous prime is 639457919. The next prime is 639457927. The reversal of 639457920 is 29754936.

It is a happy number.

639457920 is a `hidden beast` number, since 639 + 4 + 5 + 7 + 9 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (192).

It is a super-4 number, since 4×639457920⁴ (a number of 36 digits) contains 4444 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (639457927) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 106519 + ... + 112361.

Almost surely, 2^639457920 is an apocalyptic number.

639457920 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 639457920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1162371600).

639457920 is an abundant number, since it is smaller than the sum of its proper divisors (1685285280).

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

639457920 is a wasteful number, since it uses less digits than its factorization.

639457920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5887 (or 5872 counting only the distinct ones).

The product of its (nonzero) digits is 408240, while the sum is 45.

The square root of 639457920 is about 25287.5052150266. The cubic root of 639457920 is about 861.5304997956.

The spelling of 639457920 in words is "six hundred thirty-nine million, four hundred fifty-seven thousand, nine hundred twenty".