640624 has 10 divisors (see below), whose sum is σ = 1241240. Its totient is φ = 320304.

The previous prime is 640621. The next prime is 640631. The reversal of 640624 is 426046.

It is a junction number, because it is equal to n+sod(n) for n = 640595 and 640604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20004 + ... + 20035.

It is an arithmetic number, because the mean of its divisors is an integer number (124124).

2⁶⁴⁰⁶²⁴ is an apocalyptic number.

It is an amenable number.

640624 is a deficient number, since it is larger than the sum of its proper divisors (600616).

640624 is a wasteful number, since it uses less digits than its factorization.

640624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40047 (or 40041 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 22.

The square root of 640624 is about 800.3899049838. The cubic root of 640624 is about 86.2053861547.

The spelling of 640624 in words is "six hundred forty thousand, six hundred twenty-four".