81124891 has 2 divisors, whose sum is σ = 81124892. Its totient is φ = 81124890.

The previous prime is 81124859. The next prime is 81124903. The reversal of 81124891 is 19842118.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81124891 - 2⁵ = 81124859 is a prime.

It is not a weakly prime, because it can be changed into another prime (81124811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40562445 + 40562446.

It is an arithmetic number, because the mean of its divisors is an integer number (40562446).

Almost surely, 2^81124891 is an apocalyptic number.

81124891 is a deficient number, since it is larger than the sum of its proper divisors (1).

81124891 is an equidigital number, since it uses as much as digits as its factorization.

81124891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4608, while the sum is 34.

The square root of 81124891 is about 9006.9357164354. The cubic root of 81124891 is about 432.8971321968.

The spelling of 81124891 in words is "eighty-one million, one hundred twenty-four thousand, eight hundred ninety-one".