913872721 has 2 divisors, whose sum is σ = 913872722. Its totient is φ = 913872720.

The previous prime is 913872691. The next prime is 913872749. The reversal of 913872721 is 127278319.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 801512721 + 112360000 = 28311^2 + 10600^2 .

It is a cyclic number.

It is not a de Polignac number, because 913872721 - 2¹¹ = 913870673 is a prime.

It is not a weakly prime, because it can be changed into another prime (913272721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 456936360 + 456936361.

It is an arithmetic number, because the mean of its divisors is an integer number (456936361).

Almost surely, 2^913872721 is an apocalyptic number.

It is an amenable number.

913872721 is a deficient number, since it is larger than the sum of its proper divisors (1).

913872721 is an equidigital number, since it uses as much as digits as its factorization.

913872721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42336, while the sum is 40.

The square root of 913872721 is about 30230.3278348085. The cubic root of 913872721 is about 970.4248399406.

The spelling of 913872721 in words is "nine hundred thirteen million, eight hundred seventy-two thousand, seven hundred twenty-one".