721123913 has 2 divisors, whose sum is σ = 721123914. Its totient is φ = 721123912.

The previous prime is 721123877. The next prime is 721123919. The reversal of 721123913 is 319321127.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 689167504 + 31956409 = 26252^2 + 5653^2 .

It is a cyclic number.

It is not a de Polignac number, because 721123913 - 2¹⁴ = 721107529 is a prime.

It is not a weakly prime, because it can be changed into another prime (721123919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360561956 + 360561957.

It is an arithmetic number, because the mean of its divisors is an integer number (360561957).

Almost surely, 2^721123913 is an apocalyptic number.

It is an amenable number.

721123913 is a deficient number, since it is larger than the sum of its proper divisors (1).

721123913 is an equidigital number, since it uses as much as digits as its factorization.

721123913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2268, while the sum is 29.

The square root of 721123913 is about 26853.7504457012. The cubic root of 721123913 is about 896.7470688088.

The spelling of 721123913 in words is "seven hundred twenty-one million, one hundred twenty-three thousand, nine hundred thirteen".