721388624 has 40 divisors (see below), whose sum is σ = 1534523808. Its totient is φ = 325802880.

The previous prime is 721388617. The next prime is 721388627. The reversal of 721388624 is 426883127.

721388624 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×721388624² = 1040803093673226752, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721388627) 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, 14579 + ... + 40685.

Almost surely, 2^721388624 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721388624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (767261904).

721388624 is an abundant number, since it is smaller than the sum of its proper divisors (813135184).

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

721388624 is a wasteful number, since it uses less digits than its factorization.

721388624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26283 (or 26277 counting only the distinct ones).

The product of its digits is 129024, while the sum is 41.

The square root of 721388624 is about 26858.6787463568. The cubic root of 721388624 is about 896.8567817025.

The spelling of 721388624 in words is "seven hundred twenty-one million, three hundred eighty-eight thousand, six hundred twenty-four".