640564 has 6 divisors (see below), whose sum is σ = 1120994. Its totient is φ = 320280.

The previous prime is 640531. The next prime is 640579. The reversal of 640564 is 465046.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 550564 + 90000 = 742^2 + 300^2 .

It is a congruent number.

It is an unprimeable number.

640564 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80067 + ... + 80074.

2⁶⁴⁰⁵⁶⁴ is an apocalyptic number.

It is an amenable number.

640564 is a deficient number, since it is larger than the sum of its proper divisors (480430).

640564 is a wasteful number, since it uses less digits than its factorization.

640564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160145 (or 160143 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 640564 is about 800.3524223740. The cubic root of 640564 is about 86.2026947764.

The spelling of 640564 in words is "six hundred forty thousand, five hundred sixty-four".