72122721 has 32 divisors (see below), whose sum is σ = 113011200. Its totient is φ = 40423680.

The previous prime is 72122719. The next prime is 72122761. The reversal of 72122721 is 12722127.

It is not a de Polignac number, because 72122721 - 2¹ = 72122719 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 72122691 and 72122700.

It is not an unprimeable number, because it can be changed into a prime (72122711) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 32010 + ... + 34188.

It is an arithmetic number, because the mean of its divisors is an integer number (3531600).

Almost surely, 2^72122721 is an apocalyptic number.

It is an amenable number.

72122721 is a deficient number, since it is larger than the sum of its proper divisors (40888479).

72122721 is a wasteful number, since it uses less digits than its factorization.

72122721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2269.

The product of its digits is 784, while the sum is 24.

The square root of 72122721 is about 8492.5096997295. The cubic root of 72122721 is about 416.2529915286.

Adding to 72122721 its reverse (12722127), we get a palindrome (84844848).

The spelling of 72122721 in words is "seventy-two million, one hundred twenty-two thousand, seven hundred twenty-one".