721244660 has 24 divisors (see below), whose sum is σ = 1521237480. Its totient is φ = 287236224.

The previous prime is 721244651. The next prime is 721244707. The reversal of 721244660 is 66442127.

It can be written as a sum of positive squares in 4 ways, for example, as 228493456 + 492751204 = 15116^2 + 22198^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74159 + ... + 83318.

It is an arithmetic number, because the mean of its divisors is an integer number (63384895).

Almost surely, 2^721244660 is an apocalyptic number.

It is an amenable number.

721244660 is an abundant number, since it is smaller than the sum of its proper divisors (799992820).

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

721244660 is a wasteful number, since it uses less digits than its factorization.

721244660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157715 (or 157713 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 32.

The square root of 721244660 is about 26855.9985850461. The cubic root of 721244660 is about 896.7971172926.

Adding to 721244660 its reverse (66442127), we get a palindrome (787686787).

The spelling of 721244660 in words is "seven hundred twenty-one million, two hundred forty-four thousand, six hundred sixty".