639624 has 32 divisors (see below), whose sum is σ = 1656000. Its totient is φ = 205632.

The previous prime is 639601. The next prime is 639631. The reversal of 639624 is 426936.

It is a super-2 number, since 2×639624² = 818237722752, which contains 22 as substring.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 639591 and 639600.

It is an unprimeable number.

639624 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 237 + ... + 1155.

It is an arithmetic number, because the mean of its divisors is an integer number (51750).

2⁶³⁹⁶²⁴ 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 639624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (828000).

639624 is an abundant number, since it is smaller than the sum of its proper divisors (1016376).

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

639624 is a wasteful number, since it uses less digits than its factorization.

639624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 957 (or 953 counting only the distinct ones).

The product of its digits is 7776, while the sum is 30.

The square root of 639624 is about 799.7649654742. The cubic root of 639624 is about 86.1605078902.

The spelling of 639624 in words is "six hundred thirty-nine thousand, six hundred twenty-four".