721990820 has 12 divisors (see below), whose sum is σ = 1516180764. Its totient is φ = 288796320.

The previous prime is 721990817. The next prime is 721990877. The reversal of 721990820 is 28099127.

It can be written as a sum of positive squares in 2 ways, for example, as 175085824 + 546904996 = 13232^2 + 23386^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18049751 + ... + 18049790.

It is an arithmetic number, because the mean of its divisors is an integer number (126348397).

Almost surely, 2^721990820 is an apocalyptic number.

It is an amenable number.

721990820 is an abundant number, since it is smaller than the sum of its proper divisors (794189944).

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

721990820 is a wasteful number, since it uses less digits than its factorization.

721990820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36099550 (or 36099548 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 721990820 is about 26869.8868624339. The cubic root of 721990820 is about 897.1062696741.

The spelling of 721990820 in words is "seven hundred twenty-one million, nine hundred ninety thousand, eight hundred twenty".