721689413 has 2 divisors, whose sum is σ = 721689414. Its totient is φ = 721689412.

The previous prime is 721689401. The next prime is 721689481. The reversal of 721689413 is 314986127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 721620769 + 68644 = 26863^2 + 262^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721689413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721689113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360844706 + 360844707.

It is an arithmetic number, because the mean of its divisors is an integer number (360844707).

Almost surely, 2^721689413 is an apocalyptic number.

It is an amenable number.

721689413 is a deficient number, since it is larger than the sum of its proper divisors (1).

721689413 is an equidigital number, since it uses as much as digits as its factorization.

721689413 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576, while the sum is 41.

The square root of 721689413 is about 26864.2776377851. The cubic root of 721689413 is about 896.9814150188.

The spelling of 721689413 in words is "seven hundred twenty-one million, six hundred eighty-nine thousand, four hundred thirteen".