72165561 has 32 divisors (see below), whose sum is σ = 111041280. Its totient is φ = 41293824.

The previous prime is 72165557. The next prime is 72165563. The reversal of 72165561 is 16556127.

It is not a de Polignac number, because 72165561 - 2² = 72165557 is a prime.

It is not an unprimeable number, because it can be changed into a prime (72165563) 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, 58396 + ... + 59618.

It is an arithmetic number, because the mean of its divisors is an integer number (3470040).

Almost surely, 2^72165561 is an apocalyptic number.

It is an amenable number.

72165561 is a deficient number, since it is larger than the sum of its proper divisors (38875719).

72165561 is a wasteful number, since it uses less digits than its factorization.

72165561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1345.

The product of its digits is 12600, while the sum is 33.

The square root of 72165561 is about 8495.0315479108. The cubic root of 72165561 is about 416.3353915839.

The spelling of 72165561 in words is "seventy-two million, one hundred sixty-five thousand, five hundred sixty-one".