81481708687 has 2 divisors, whose sum is σ = 81481708688. Its totient is φ = 81481708686.

The previous prime is 81481708669. The next prime is 81481708723. The reversal of 81481708687 is 78680718418.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81481708687 - 2⁷ = 81481708559 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81481708387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40740854343 + 40740854344.

It is an arithmetic number, because the mean of its divisors is an integer number (40740854344).

Almost surely, 2^81481708687 is an apocalyptic number.

81481708687 is a deficient number, since it is larger than the sum of its proper divisors (1).

81481708687 is an equidigital number, since it uses as much as digits as its factorization.

81481708687 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4816896, while the sum is 58.

The spelling of 81481708687 in words is "eighty-one billion, four hundred eighty-one million, seven hundred eight thousand, six hundred eighty-seven".