81087631 has 2 divisors, whose sum is σ = 81087632. Its totient is φ = 81087630.

The previous prime is 81087623. The next prime is 81087641. The reversal of 81087631 is 13678018.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81087631 - 2³ = 81087623 is a prime.

It is a super-2 number, since 2×81087631² = 13150407802384322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81087641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40543815 + 40543816.

It is an arithmetic number, because the mean of its divisors is an integer number (40543816).

Almost surely, 2^81087631 is an apocalyptic number.

81087631 is a deficient number, since it is larger than the sum of its proper divisors (1).

81087631 is an equidigital number, since it uses as much as digits as its factorization.

81087631 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8064, while the sum is 34.

The square root of 81087631 is about 9004.8670728668. The cubic root of 81087631 is about 432.8308466750.

It can be divided in two parts, 81087 and 631, that added together give a palindrome (81718).

The spelling of 81087631 in words is "eighty-one million, eighty-seven thousand, six hundred thirty-one".