81797716009 has 9 divisors (see below), whose sum is σ = 82560615319. Its totient is φ = 81041810080.

The previous prime is 81797715983. The next prime is 81797716027. The reversal of 81797716009 is 90061779718.

The square root of 81797716009 is 286003.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 1441341225 + 80356374784 = 37965^2 + 283472^2 .

It is not a de Polignac number, because 81797716009 - 2⁵ = 81797715977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81797717009) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 32317074 + ... + 32319604.

Almost surely, 2^81797716009 is an apocalyptic number.

81797716009 is the 286003-rd square number.

81797716009 is the 143002-nd centered octagonal number.

It is an amenable number.

81797716009 is a deficient number, since it is larger than the sum of its proper divisors (762899310).

81797716009 is an frugal number, since it uses more digits than its factorization.

81797716009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5288 (or 2644 counting only the distinct ones).

The product of its (nonzero) digits is 1333584, while the sum is 55.

It can be divided in two parts, 817977 and 16009, that added together give a triangular number (833986 = T₁₂₉₁).

The spelling of 81797716009 in words is "eighty-one billion, seven hundred ninety-seven million, seven hundred sixteen thousand, nine".