81292521 has 12 divisors (see below), whose sum is σ = 115142192. Its totient is φ = 51006528.

The previous prime is 81292517. The next prime is 81292529. The reversal of 81292521 is 12529218.

It is not a de Polignac number, because 81292521 - 2² = 81292517 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81292529) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 46015 + ... + 47748.

Almost surely, 2^81292521 is an apocalyptic number.

It is an amenable number.

81292521 is a deficient number, since it is larger than the sum of its proper divisors (33849671).

81292521 is a wasteful number, since it uses less digits than its factorization.

81292521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93800 (or 93783 counting only the distinct ones).

The product of its digits is 2880, while the sum is 30.

The square root of 81292521 is about 9016.2365208550. The cubic root of 81292521 is about 433.1950950899.

The spelling of 81292521 in words is "eighty-one million, two hundred ninety-two thousand, five hundred twenty-one".