81717071651 has 2 divisors, whose sum is σ = 81717071652. Its totient is φ = 81717071650.

The previous prime is 81717071647. The next prime is 81717071719. The reversal of 81717071651 is 15617071718.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81717071651 - 2² = 81717071647 is a prime.

It is not a weakly prime, because it can be changed into another prime (81717071551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40858535825 + 40858535826.

It is an arithmetic number, because the mean of its divisors is an integer number (40858535826).

Almost surely, 2^81717071651 is an apocalyptic number.

81717071651 is a deficient number, since it is larger than the sum of its proper divisors (1).

81717071651 is an equidigital number, since it uses as much as digits as its factorization.

81717071651 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 82320, while the sum is 44.

The spelling of 81717071651 in words is "eighty-one billion, seven hundred seventeen million, seventy-one thousand, six hundred fifty-one".