81702557897 has 2 divisors, whose sum is σ = 81702557898. Its totient is φ = 81702557896.

The previous prime is 81702557879. The next prime is 81702557929. The reversal of 81702557897 is 79875520718.

Together with previous prime (81702557879) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80908389136 + 794168761 = 284444^2 + 28181^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81702557897 is a prime.

It is not a weakly prime, because it can be changed into another prime (81702527897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40851278948 + 40851278949.

It is an arithmetic number, because the mean of its divisors is an integer number (40851278949).

Almost surely, 2^81702557897 is an apocalyptic number.

It is an amenable number.

81702557897 is a deficient number, since it is larger than the sum of its proper divisors (1).

81702557897 is an equidigital number, since it uses as much as digits as its factorization.

81702557897 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9878400, while the sum is 59.

The spelling of 81702557897 in words is "eighty-one billion, seven hundred two million, five hundred fifty-seven thousand, eight hundred ninety-seven".