721555516 has 12 divisors (see below), whose sum is σ = 1377515160. Its totient is φ = 327979760.

The previous prime is 721555487. The next prime is 721555559. The reversal of 721555516 is 615555127.

It is a congruent number.

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, 8199451 + ... + 8199538.

It is an arithmetic number, because the mean of its divisors is an integer number (114792930).

Almost surely, 2^721555516 is an apocalyptic number.

It is an amenable number.

721555516 is a deficient number, since it is larger than the sum of its proper divisors (655959644).

721555516 is a wasteful number, since it uses less digits than its factorization.

721555516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16399004 (or 16399002 counting only the distinct ones).

The product of its digits is 52500, while the sum is 37.

The square root of 721555516 is about 26861.7854209284. The cubic root of 721555516 is about 896.9259384537.

The spelling of 721555516 in words is "seven hundred twenty-one million, five hundred fifty-five thousand, five hundred sixteen".