721613266 has 12 divisors (see below), whose sum is σ = 1189767726. Its totient is φ = 328005920.

The previous prime is 721613237. The next prime is 721613273. The reversal of 721613266 is 662316127.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 606587641 + 115025625 = 24629^2 + 10725^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1490695 + ... + 1491178.

Almost surely, 2^721613266 is an apocalyptic number.

721613266 is a deficient number, since it is larger than the sum of its proper divisors (468154460).

721613266 is a wasteful number, since it uses less digits than its factorization.

721613266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2981897 (or 2981886 counting only the distinct ones).

The product of its digits is 18144, while the sum is 34.

The square root of 721613266 is about 26862.8603465826. The cubic root of 721613266 is about 896.9498664306.

The spelling of 721613266 in words is "seven hundred twenty-one million, six hundred thirteen thousand, two hundred sixty-six".