72239721 has 4 divisors (see below), whose sum is σ = 96319632. Its totient is φ = 48159812.

The previous prime is 72239719. The next prime is 72239743. The reversal of 72239721 is 12793227.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12793227 = 3 ⋅4264409.

It is a cyclic number.

It is not a de Polignac number, because 72239721 - 2¹ = 72239719 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (72239701) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12039951 + ... + 12039956.

It is an arithmetic number, because the mean of its divisors is an integer number (24079908).

Almost surely, 2^72239721 is an apocalyptic number.

It is an amenable number.

72239721 is a deficient number, since it is larger than the sum of its proper divisors (24079911).

72239721 is a wasteful number, since it uses less digits than its factorization.

72239721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24079910.

The product of its digits is 10584, while the sum is 33.

The square root of 72239721 is about 8499.3953314339. The cubic root of 72239721 is about 416.4779566431.

The spelling of 72239721 in words is "seventy-two million, two hundred thirty-nine thousand, seven hundred twenty-one".