72137561 has 2 divisors, whose sum is σ = 72137562. Its totient is φ = 72137560.

The previous prime is 72137557. The next prime is 72137599. The reversal of 72137561 is 16573127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 49632025 + 22505536 = 7045^2 + 4744^2 .

It is a cyclic number.

It is not a de Polignac number, because 72137561 - 2² = 72137557 is a prime.

It is not a weakly prime, because it can be changed into another prime (72137501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36068780 + 36068781.

It is an arithmetic number, because the mean of its divisors is an integer number (36068781).

Almost surely, 2^72137561 is an apocalyptic number.

It is an amenable number.

72137561 is a deficient number, since it is larger than the sum of its proper divisors (1).

72137561 is an equidigital number, since it uses as much as digits as its factorization.

72137561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8820, while the sum is 32.

The square root of 72137561 is about 8493.3833658914. The cubic root of 72137561 is about 416.2815390315.

The spelling of 72137561 in words is "seventy-two million, one hundred thirty-seven thousand, five hundred sixty-one".