639504540 has 72 divisors (see below), whose sum is σ = 1972741680. Its totient is φ = 167641344.

The previous prime is 639504533. The next prime is 639504587. The reversal of 639504540 is 45405936.

It is a happy number.

639504540 is a `hidden beast` number, since 63 + 9 + 50 + 4 + 540 = 666.

It is a super-2 number, since 2×639504540² = 817932113361223200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 639504495 and 639504504.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19489 + ... + 40728.

It is an arithmetic number, because the mean of its divisors is an integer number (27399190).

Almost surely, 2^639504540 is an apocalyptic number.

639504540 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

639504540 is an abundant number, since it is smaller than the sum of its proper divisors (1333237140).

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

639504540 is a wasteful number, since it uses less digits than its factorization.

639504540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60291 (or 60286 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 36.

The square root of 639504540 is about 25288.4269973441. The cubic root of 639504540 is about 861.5514360577.

The spelling of 639504540 in words is "six hundred thirty-nine million, five hundred four thousand, five hundred forty".