81788831 has 2 divisors, whose sum is σ = 81788832. Its totient is φ = 81788830.

The previous prime is 81788827. The next prime is 81788867. The reversal of 81788831 is 13888718.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81788831 - 2² = 81788827 is a prime.

It is a super-2 number, since 2×81788831² = 13378825752693122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81788821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40894415 + 40894416.

It is an arithmetic number, because the mean of its divisors is an integer number (40894416).

Almost surely, 2^81788831 is an apocalyptic number.

81788831 is a deficient number, since it is larger than the sum of its proper divisors (1).

81788831 is an equidigital number, since it uses as much as digits as its factorization.

81788831 is an evil number, because the sum of its binary digits is even.

The product of its digits is 86016, while the sum is 44.

The square root of 81788831 is about 9043.7177642826. The cubic root of 81788831 is about 434.0748931044.

The spelling of 81788831 in words is "eighty-one million, seven hundred eighty-eight thousand, eight hundred thirty-one".