81702557879 has 2 divisors, whose sum is σ = 81702557880. Its totient is φ = 81702557878.

The previous prime is 81702557869. The next prime is 81702557897. The reversal of 81702557879 is 97875520718.

Together with next prime (81702557897) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81702557879 - 2³² = 77407590583 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81702557869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40851278939 + 40851278940.

It is an arithmetic number, because the mean of its divisors is an integer number (40851278940).

Almost surely, 2^81702557879 is an apocalyptic number.

81702557879 is a deficient number, since it is larger than the sum of its proper divisors (1).

81702557879 is an equidigital number, since it uses as much as digits as its factorization.

81702557879 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 81702557879 in words is "eighty-one billion, seven hundred two million, five hundred fifty-seven thousand, eight hundred seventy-nine".