721667620 has 12 divisors (see below), whose sum is σ = 1515502044. Its totient is φ = 288667040.

The previous prime is 721667537. The next prime is 721667651. The reversal of 721667620 is 26766127.

It can be written as a sum of positive squares in 2 ways, for example, as 328914496 + 392753124 = 18136^2 + 19818^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 721667620.

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, 18041671 + ... + 18041710.

It is an arithmetic number, because the mean of its divisors is an integer number (126291837).

Almost surely, 2^721667620 is an apocalyptic number.

It is an amenable number.

721667620 is an abundant number, since it is smaller than the sum of its proper divisors (793834424).

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

721667620 is a wasteful number, since it uses less digits than its factorization.

721667620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36083390 (or 36083388 counting only the distinct ones).

The product of its (nonzero) digits is 42336, while the sum is 37.

The square root of 721667620 is about 26863.8720217321. The cubic root of 721667620 is about 896.9723861520.

The spelling of 721667620 in words is "seven hundred twenty-one million, six hundred sixty-seven thousand, six hundred twenty".