81908887 has 2 divisors, whose sum is σ = 81908888. Its totient is φ = 81908886.

The previous prime is 81908881. The next prime is 81908891. The reversal of 81908887 is 78880918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81908887 - 2⁷ = 81908759 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81908887.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81908881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40954443 + 40954444.

It is an arithmetic number, because the mean of its divisors is an integer number (40954444).

Almost surely, 2^81908887 is an apocalyptic number.

81908887 is a deficient number, since it is larger than the sum of its proper divisors (1).

81908887 is an equidigital number, since it uses as much as digits as its factorization.

81908887 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 258048, while the sum is 49.

The square root of 81908887 is about 9050.3528660489. The cubic root of 81908887 is about 434.2871788849.

The spelling of 81908887 in words is "eighty-one million, nine hundred eight thousand, eight hundred eighty-seven".