81675352521 has 81 divisors (see below), whose sum is σ = 142130374893. Its totient is φ = 45063209520.

The previous prime is 81675352513. The next prime is 81675352559. The reversal of 81675352521 is 12525357618.

The square root of 81675352521 is 285789.

It is a perfect power (a square), and thus also a powerful number.

81675352521 is a `hidden beast` number, since 8 + 1 + 6 + 75 + 3 + 52 + 521 = 666.

It is not a de Polignac number, because 81675352521 - 2³ = 81675352513 is a prime.

Its product of digits (504000) is a multiple of the sum of its prime divisors (480).

It is not an unprimeable number, because it can be changed into a prime (81675352501) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 186048420 + ... + 186048858.

Almost surely, 2^81675352521 is an apocalyptic number.

81675352521 is the 285789-th square number.

81675352521 is the 142895-th centered octagonal number.

It is an amenable number.

81675352521 is a deficient number, since it is larger than the sum of its proper divisors (60455022372).

81675352521 is an equidigital number, since it uses as much as digits as its factorization.

81675352521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 960 (or 480 counting only the distinct ones).

The product of its digits is 504000, while the sum is 45.

The spelling of 81675352521 in words is "eighty-one billion, six hundred seventy-five million, three hundred fifty-two thousand, five hundred twenty-one".