72721161 has 12 divisors (see below), whose sum is σ = 105185392. Its totient is φ = 48414456.

The previous prime is 72721157. The next prime is 72721163. The reversal of 72721161 is 16112727.

It is not a de Polignac number, because 72721161 - 2² = 72721157 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72721163) 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 11 ways as a sum of consecutive naturals, for example, 1950 + ... + 12216.

Almost surely, 2^72721161 is an apocalyptic number.

It is an amenable number.

72721161 is a deficient number, since it is larger than the sum of its proper divisors (32464231).

72721161 is a wasteful number, since it uses less digits than its factorization.

72721161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11060 (or 11057 counting only the distinct ones).

The product of its digits is 1176, while the sum is 27.

The square root of 72721161 is about 8527.6703149219. The cubic root of 72721161 is about 417.4011115548.

Adding to 72721161 its reverse (16112727), we get a palindrome (88833888).

The spelling of 72721161 in words is "seventy-two million, seven hundred twenty-one thousand, one hundred sixty-one".