721564 has 6 divisors (see below), whose sum is σ = 1262744. Its totient is φ = 360780.

The previous prime is 721561. The next prime is 721571. The reversal of 721564 is 465127.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90192 + ... + 90199.

2⁷²¹⁵⁶⁴ is an apocalyptic number.

It is an amenable number.

721564 is a deficient number, since it is larger than the sum of its proper divisors (541180).

721564 is a wasteful number, since it uses less digits than its factorization.

721564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180395 (or 180393 counting only the distinct ones).

The product of its digits is 1680, while the sum is 25.

The square root of 721564 is about 849.4492333271. The cubic root of 721564 is about 89.6929453771.

The spelling of 721564 in words is "seven hundred twenty-one thousand, five hundred sixty-four".