81307881 has 20 divisors (see below), whose sum is σ = 121923472. Its totient is φ = 53998488.

The previous prime is 81307873. The next prime is 81307927. The reversal of 81307881 is 18870318.

It is not a de Polignac number, because 81307881 - 2³ = 81307873 is a prime.

It is a super-2 number, since 2×81307881² = 13221943025420322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81307801) 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 19 ways as a sum of consecutive naturals, for example, 21150 + ... + 24696.

Almost surely, 2^81307881 is an apocalyptic number.

81307881 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

81307881 is a deficient number, since it is larger than the sum of its proper divisors (40615591).

81307881 is a wasteful number, since it uses less digits than its factorization.

81307881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3842 (or 3833 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The square root of 81307881 is about 9017.0882772656. The cubic root of 81307881 is about 433.2223770487. Note that the first 3 decimals are identical.

The spelling of 81307881 in words is "eighty-one million, three hundred seven thousand, eight hundred eighty-one".