72510721 has 2 divisors, whose sum is σ = 72510722. Its totient is φ = 72510720.

The previous prime is 72510689. The next prime is 72510749. The reversal of 72510721 is 12701527.

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., 49843600 + 22667121 = 7060^2 + 4761^2 .

It is an emirp because it is prime and its reverse (12701527) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 72510721 - 2⁵ = 72510689 is a prime.

It is not a weakly prime, because it can be changed into another prime (72510791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36255360 + 36255361.

It is an arithmetic number, because the mean of its divisors is an integer number (36255361).

Almost surely, 2^72510721 is an apocalyptic number.

It is an amenable number.

72510721 is a deficient number, since it is larger than the sum of its proper divisors (1).

72510721 is an equidigital number, since it uses as much as digits as its factorization.

72510721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 72510721 is about 8515.3227184881. The cubic root of 72510721 is about 416.9980983951.

The spelling of 72510721 in words is "seventy-two million, five hundred ten thousand, seven hundred twenty-one".