721644313 has 8 divisors (see below), whose sum is σ = 777590856. Its totient is φ = 665760000.

The previous prime is 721644311. The next prime is 721644317. The reversal of 721644313 is 313446127.

It can be written as a sum of positive squares in 4 ways, for example, as 14722569 + 706921744 = 3837^2 + 26588^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 721644313 - 2¹ = 721644311 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721644311) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10113 + ... + 39313.

It is an arithmetic number, because the mean of its divisors is an integer number (97198857).

Almost surely, 2^721644313 is an apocalyptic number.

It is an amenable number.

721644313 is a deficient number, since it is larger than the sum of its proper divisors (55946543).

721644313 is a wasteful number, since it uses less digits than its factorization.

721644313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31115.

The product of its digits is 12096, while the sum is 31.

The square root of 721644313 is about 26863.4382200045. The cubic root of 721644313 is about 896.9627298320.

It can be divided in two parts, 7216 and 44313, that added together give a square (51529 = 227²).

The spelling of 721644313 in words is "seven hundred twenty-one million, six hundred forty-four thousand, three hundred thirteen".