81080891 has 2 divisors, whose sum is σ = 81080892. Its totient is φ = 81080890.

The previous prime is 81080861. The next prime is 81080893. The reversal of 81080891 is 19808018.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81080891 - 2²⁶ = 13972027 is a prime.

It is a super-2 number, since 2×81080891² = 13148221770707762, which contains 22 as substring.

Together with 81080893, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81080893) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40540445 + 40540446.

It is an arithmetic number, because the mean of its divisors is an integer number (40540446).

Almost surely, 2^81080891 is an apocalyptic number.

81080891 is a deficient number, since it is larger than the sum of its proper divisors (1).

81080891 is an equidigital number, since it uses as much as digits as its factorization.

81080891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4608, while the sum is 35.

The square root of 81080891 is about 9004.4928230301. The cubic root of 81080891 is about 432.8188540497.

The spelling of 81080891 in words is "eighty-one million, eighty thousand, eight hundred ninety-one".