639564 has 24 divisors (see below), whose sum is σ = 1505280. Its totient is φ = 211344.

The previous prime is 639563. The next prime is 639571. The reversal of 639564 is 465936.

It is a happy number.

It is a super-2 number, since 2×639564² = 818084220192, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (639563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2557 + ... + 2795.

It is an arithmetic number, because the mean of its divisors is an integer number (62720).

2⁶³⁹⁵⁶⁴ is an apocalyptic number.

It is an amenable number.

639564 is an abundant number, since it is smaller than the sum of its proper divisors (865716).

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

639564 is a wasteful number, since it uses less digits than its factorization.

639564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 469 (or 467 counting only the distinct ones).

The product of its digits is 19440, while the sum is 33.

The square root of 639564 is about 799.7274535740. The cubic root of 639564 is about 86.1578137073.

The spelling of 639564 in words is "six hundred thirty-nine thousand, five hundred sixty-four".