72457721 has 8 divisors (see below), whose sum is σ = 84499200. Its totient is φ = 62106324.

The previous prime is 72457717. The next prime is 72457727. The reversal of 72457721 is 12775427.

It is not a de Polignac number, because 72457721 - 2² = 72457717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72457727) 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, 105281 + ... + 105966.

It is an arithmetic number, because the mean of its divisors is an integer number (10562400).

Almost surely, 2^72457721 is an apocalyptic number.

It is an amenable number.

72457721 is a deficient number, since it is larger than the sum of its proper divisors (12041479).

72457721 is an equidigital number, since it uses as much as digits as its factorization.

72457721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211268 (or 211254 counting only the distinct ones).

The product of its digits is 27440, while the sum is 35.

The square root of 72457721 is about 8512.2101125383. The cubic root of 72457721 is about 416.8964753256.

The spelling of 72457721 in words is "seventy-two million, four hundred fifty-seven thousand, seven hundred twenty-one".