72557809 has 2 divisors, whose sum is σ = 72557810. Its totient is φ = 72557808.

The previous prime is 72557791. The next prime is 72557833. The reversal of 72557809 is 90875527.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72335025 + 222784 = 8505^2 + 472^2 .

It is a cyclic number.

It is not a de Polignac number, because 72557809 - 2¹¹ = 72555761 is a prime.

It is not a weakly prime, because it can be changed into another prime (72557869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36278904 + 36278905.

It is an arithmetic number, because the mean of its divisors is an integer number (36278905).

Almost surely, 2^72557809 is an apocalyptic number.

It is an amenable number.

72557809 is a deficient number, since it is larger than the sum of its proper divisors (1).

72557809 is an equidigital number, since it uses as much as digits as its factorization.

72557809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 176400, while the sum is 43.

The square root of 72557809 is about 8518.0871679034. The cubic root of 72557809 is about 417.0883441652.

The spelling of 72557809 in words is "seventy-two million, five hundred fifty-seven thousand, eight hundred nine".