72872721 has 24 divisors (see below), whose sum is σ = 110171880. Its totient is φ = 46365696.

The previous prime is 72872719. The next prime is 72872731. The reversal of 72872721 is 12727827.

It can be written as a sum of positive squares in 4 ways, for example, as 34680321 + 38192400 = 5889^2 + 6180^2 .

It is not a de Polignac number, because 72872721 - 2¹ = 72872719 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (72872731) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15585 + ... + 19713.

It is an arithmetic number, because the mean of its divisors is an integer number (4590495).

Almost surely, 2^72872721 is an apocalyptic number.

It is an amenable number.

72872721 is a deficient number, since it is larger than the sum of its proper divisors (37299159).

72872721 is a wasteful number, since it uses less digits than its factorization.

72872721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4225 (or 4222 counting only the distinct ones).

The product of its digits is 21952, while the sum is 36.

The square root of 72872721 is about 8536.5520557190. The cubic root of 72872721 is about 417.6908823920.

The spelling of 72872721 in words is "seventy-two million, eight hundred seventy-two thousand, seven hundred twenty-one".