72531521 has 2 divisors, whose sum is σ = 72531522. Its totient is φ = 72531520.

The previous prime is 72531463. The next prime is 72531539. The reversal of 72531521 is 12513527.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66650896 + 5880625 = 8164^2 + 2425^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72531521 is a prime.

It is not a weakly prime, because it can be changed into another prime (72531421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36265760 + 36265761.

It is an arithmetic number, because the mean of its divisors is an integer number (36265761).

Almost surely, 2^72531521 is an apocalyptic number.

It is an amenable number.

72531521 is a deficient number, since it is larger than the sum of its proper divisors (1).

72531521 is an equidigital number, since it uses as much as digits as its factorization.

72531521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2100, while the sum is 26.

The square root of 72531521 is about 8516.5439586724. The cubic root of 72531521 is about 417.0379671258.

The spelling of 72531521 in words is "seventy-two million, five hundred thirty-one thousand, five hundred twenty-one".