72165321 has 6 divisors (see below), whose sum is σ = 104238810. Its totient is φ = 48110208.

The previous prime is 72165307. The next prime is 72165377. The reversal of 72165321 is 12356127.

It is a happy number.

72165321 is a `hidden beast` number, since 7 + 2 + 1 + 653 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 69806025 + 2359296 = 8355^2 + 1536^2 .

It is not a de Polignac number, because 72165321 - 2¹⁰ = 72164297 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (72145321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4009176 + ... + 4009193.

It is an arithmetic number, because the mean of its divisors is an integer number (17373135).

Almost surely, 2^72165321 is an apocalyptic number.

It is an amenable number.

72165321 is a deficient number, since it is larger than the sum of its proper divisors (32073489).

72165321 is a wasteful number, since it uses less digits than its factorization.

72165321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8018375 (or 8018372 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 72165321 is about 8495.0174219951. The cubic root of 72165321 is about 416.3349300498.

The spelling of 72165321 in words is "seventy-two million, one hundred sixty-five thousand, three hundred twenty-one".