72521257 has 4 divisors (see below), whose sum is σ = 75022020. Its totient is φ = 70020496.

The previous prime is 72521243. The next prime is 72521261. The reversal of 72521257 is 75212527.

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 13169641 + 59351616 = 3629^2 + 7704^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72521257 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72521237) 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, 1250338 + ... + 1250395.

It is an arithmetic number, because the mean of its divisors is an integer number (18755505).

Almost surely, 2^72521257 is an apocalyptic number.

It is an amenable number.

72521257 is a deficient number, since it is larger than the sum of its proper divisors (2500763).

72521257 is a wasteful number, since it uses less digits than its factorization.

72521257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2500762.

The product of its digits is 9800, while the sum is 31.

The square root of 72521257 is about 8515.9413455002. The cubic root of 72521257 is about 417.0182943934.

The spelling of 72521257 in words is "seventy-two million, five hundred twenty-one thousand, two hundred fifty-seven".