639228408 has 128 divisors (see below), whose sum is σ = 1974174720. Its totient is φ = 167961600.

The previous prime is 639228371. The next prime is 639228413. The reversal of 639228408 is 804822936.

It is a super-2 number, since 2×639228408² = 817225915188428928, which contains 22 as substring.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 639228408.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1063308 + ... + 1063908.

It is an arithmetic number, because the mean of its divisors is an integer number (15423240).

Almost surely, 2^639228408 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639228408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (987087360).

639228408 is an abundant number, since it is smaller than the sum of its proper divisors (1334946312).

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

639228408 is a wasteful number, since it uses less digits than its factorization.

639228408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1117 (or 1113 counting only the distinct ones).

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

The square root of 639228408 is about 25282.9667562966. The cubic root of 639228408 is about 861.4274149571.

The spelling of 639228408 in words is "six hundred thirty-nine million, two hundred twenty-eight thousand, four hundred eight".