81675021 has 16 divisors (see below), whose sum is σ = 118425024. Its totient is φ = 49860864.

The previous prime is 81675007. The next prime is 81675023. The reversal of 81675021 is 12057618.

It is not a de Polignac number, because 81675021 - 2¹³ = 81666829 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81675021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81675023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19755 + ... + 23528.

It is an arithmetic number, because the mean of its divisors is an integer number (7401564).

Almost surely, 2^81675021 is an apocalyptic number.

It is an amenable number.

81675021 is a deficient number, since it is larger than the sum of its proper divisors (36750003).

81675021 is a wasteful number, since it uses less digits than its factorization.

81675021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43340.

The product of its (nonzero) digits is 3360, while the sum is 30.

The square root of 81675021 is about 9037.4233606709. The cubic root of 81675021 is about 433.8734597497.

The spelling of 81675021 in words is "eighty-one million, six hundred seventy-five thousand, twenty-one".