81717722677 has 2 divisors, whose sum is σ = 81717722678. Its totient is φ = 81717722676.

The previous prime is 81717722641. The next prime is 81717722717. The reversal of 81717722677 is 77622771718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65778912676 + 15938810001 = 256474^2 + 126249^2 .

It is a cyclic number.

It is not a de Polignac number, because 81717722677 - 2²⁷ = 81583504949 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81717722627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40858861338 + 40858861339.

It is an arithmetic number, because the mean of its divisors is an integer number (40858861339).

Almost surely, 2^81717722677 is an apocalyptic number.

It is an amenable number.

81717722677 is a deficient number, since it is larger than the sum of its proper divisors (1).

81717722677 is an equidigital number, since it uses as much as digits as its factorization.

81717722677 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3226944, while the sum is 55.

The spelling of 81717722677 in words is "eighty-one billion, seven hundred seventeen million, seven hundred twenty-two thousand, six hundred seventy-seven".