639971400 has 48 divisors (see below), whose sum is σ = 1983913200. Its totient is φ = 170658880.

The previous prime is 639971399. The next prime is 639971401. The reversal of 639971400 is 4179936.

It is an interprime number because it is at equal distance from previous prime (639971399) and next prime (639971401).

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (639971401) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 532710 + ... + 533909.

It is an arithmetic number, because the mean of its divisors is an integer number (41331525).

Almost surely, 2^639971400 is an apocalyptic number.

639971400 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

639971400 is an abundant number, since it is smaller than the sum of its proper divisors (1343941800).

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

639971400 is a wasteful number, since it uses less digits than its factorization.

639971400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1066638 (or 1066629 counting only the distinct ones).

The product of its (nonzero) digits is 40824, while the sum is 39.

The square root of 639971400 is about 25297.6560179002. The cubic root of 639971400 is about 861.7610389815.

The spelling of 639971400 in words is "six hundred thirty-nine million, nine hundred seventy-one thousand, four hundred".