721270621 has 4 divisors (see below), whose sum is σ = 722141500. Its totient is φ = 720399744.

The previous prime is 721270619. The next prime is 721270631. The reversal of 721270621 is 126072127.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 182520100 + 538750521 = 13510^2 + 23211^2 .

It is a cyclic number.

It is not a de Polignac number, because 721270621 - 2¹ = 721270619 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 721270621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721270631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 434196 + ... + 435853.

It is an arithmetic number, because the mean of its divisors is an integer number (180535375).

Almost surely, 2^721270621 is an apocalyptic number.

It is an amenable number.

721270621 is a deficient number, since it is larger than the sum of its proper divisors (870879).

721270621 is an equidigital number, since it uses as much as digits as its factorization.

721270621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 870878.

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 721270621 is about 26856.4819177792. The cubic root of 721270621 is about 896.8078771507.

The spelling of 721270621 in words is "seven hundred twenty-one million, two hundred seventy thousand, six hundred twenty-one".