72637561 has 2 divisors, whose sum is σ = 72637562. Its totient is φ = 72637560.

The previous prime is 72637531. The next prime is 72637571. The reversal of 72637561 is 16573627.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 38192400 + 34445161 = 6180^2 + 5869^2 .

It is a cyclic number.

It is not a de Polignac number, because 72637561 - 2¹¹ = 72635513 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 72637561.

It is not a weakly prime, because it can be changed into another prime (72637531) 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 as a sum of consecutive naturals, namely, 36318780 + 36318781.

It is an arithmetic number, because the mean of its divisors is an integer number (36318781).

Almost surely, 2^72637561 is an apocalyptic number.

It is an amenable number.

72637561 is a deficient number, since it is larger than the sum of its proper divisors (1).

72637561 is an equidigital number, since it uses as much as digits as its factorization.

72637561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 52920, while the sum is 37.

The square root of 72637561 is about 8522.7672149367. The cubic root of 72637561 is about 417.2411025899.

The spelling of 72637561 in words is "seventy-two million, six hundred thirty-seven thousand, five hundred sixty-one".