721244736 has 105 divisors (see below), whose sum is σ = 2143742601. Its totient is φ = 239770368.

The previous prime is 721244717. The next prime is 721244753. The reversal of 721244736 is 637442127.

The square root of 721244736 is 26856.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 392040000 + 329204736 = 19800^2 + 18144^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 721244736.

It is an unprimeable number.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 1933446 + ... + 1933818.

Almost surely, 2^721244736 is an apocalyptic number.

721244736 is the 26856-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721244736

721244736 is an abundant number, since it is smaller than the sum of its proper divisors (1422497865).

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

721244736 is an frugal number, since it uses more digits than its factorization.

721244736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 770 (or 378 counting only the distinct ones).

The product of its digits is 56448, while the sum is 36.

The cubic root of 721244736 is about 896.7971487921.

Multiplying 721244736 by its sum of digits (36), we get a square (25964810496 = 161136²).

721244736 divided by its sum of digits (36) gives a square (20034576 = 4476²).

The spelling of 721244736 in words is "seven hundred twenty-one million, two hundred forty-four thousand, seven hundred thirty-six".