81887831 has 2 divisors, whose sum is σ = 81887832. Its totient is φ = 81887830.

The previous prime is 81887821. The next prime is 81887837. The reversal of 81887831 is 13878818.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81887831 is a prime.

It is a super-2 number, since 2×81887831² = 13411233731769122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81887837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40943915 + 40943916.

It is an arithmetic number, because the mean of its divisors is an integer number (40943916).

Almost surely, 2^81887831 is an apocalyptic number.

81887831 is a deficient number, since it is larger than the sum of its proper divisors (1).

81887831 is an equidigital number, since it uses as much as digits as its factorization.

81887831 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 81887831 is about 9049.1895217196. The cubic root of 81887831 is about 434.2499621886.

The spelling of 81887831 in words is "eighty-one million, eight hundred eighty-seven thousand, eight hundred thirty-one".