721568 has 12 divisors (see below), whose sum is σ = 1420650. Its totient is φ = 360768.

The previous prime is 721561. The next prime is 721571. The reversal of 721568 is 865127.

It can be written as a sum of positive squares in only one way, i.e., 394384 + 327184 = 628^2 + 572^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 721568.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721568.

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, 11243 + ... + 11306.

2⁷²¹⁵⁶⁸ is an apocalyptic number.

It is an amenable number.

721568 is a deficient number, since it is larger than the sum of its proper divisors (699082).

721568 is a wasteful number, since it uses less digits than its factorization.

721568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22559 (or 22551 counting only the distinct ones).

The product of its digits is 3360, while the sum is 29.

The square root of 721568 is about 849.4515877906. The cubic root of 721568 is about 89.6931111148.

It can be divided in two parts, 72 and 1568, that multiplied together give a square (112896 = 336²).

The spelling of 721568 in words is "seven hundred twenty-one thousand, five hundred sixty-eight".