72656321 has 4 divisors (see below), whose sum is σ = 72712644. Its totient is φ = 72600000.

The previous prime is 72656267. The next prime is 72656329. The reversal of 72656321 is 12365627.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 30924721 + 41731600 = 5561^2 + 6460^2 .

It is a cyclic number.

It is not a de Polignac number, because 72656321 - 2⁶ = 72656257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72656329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26180 + ... + 28821.

It is an arithmetic number, because the mean of its divisors is an integer number (18178161).

Almost surely, 2^72656321 is an apocalyptic number.

It is an amenable number.

72656321 is a deficient number, since it is larger than the sum of its proper divisors (56323).

72656321 is a wasteful number, since it uses less digits than its factorization.

72656321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56322.

The product of its digits is 15120, while the sum is 32.

The square root of 72656321 is about 8523.8677253932. The cubic root of 72656321 is about 417.2770195876.

The spelling of 72656321 in words is "seventy-two million, six hundred fifty-six thousand, three hundred twenty-one".