72591521 has 4 divisors (see below), whose sum is σ = 74553492. Its totient is φ = 70629552.

The previous prime is 72591517. The next prime is 72591527. The reversal of 72591521 is 12519527.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 50922496 + 21669025 = 7136^2 + 4655^2 .

It is a cyclic number.

It is not a de Polignac number, because 72591521 - 2² = 72591517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72591527) 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 3 ways as a sum of consecutive naturals, for example, 980930 + ... + 981003.

It is an arithmetic number, because the mean of its divisors is an integer number (18638373).

Almost surely, 2^72591521 is an apocalyptic number.

It is an amenable number.

72591521 is a deficient number, since it is larger than the sum of its proper divisors (1961971).

72591521 is a wasteful number, since it uses less digits than its factorization.

72591521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1961970.

The product of its digits is 6300, while the sum is 32.

The square root of 72591521 is about 8520.0657861310. The cubic root of 72591521 is about 417.1529303912.

The spelling of 72591521 in words is "seventy-two million, five hundred ninety-one thousand, five hundred twenty-one".