81597636409 has 9 divisors (see below), whose sum is σ = 81939847269. Its totient is φ = 81256852380.

The previous prime is 81597636377. The next prime is 81597636413. The reversal of 81597636409 is 90463679518.

The square root of 81597636409 is 285653.

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

It is not a de Polignac number, because 81597636409 - 2⁵ = 81597636377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81597630409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 94550712 + ... + 94551574.

Almost surely, 2^81597636409 is an apocalyptic number.

81597636409 is the 285653-rd square number.

81597636409 is the 142827-th centered octagonal number.

It is an amenable number.

81597636409 is a deficient number, since it is larger than the sum of its proper divisors (342210860).

81597636409 is an frugal number, since it uses more digits than its factorization.

81597636409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2388 (or 1194 counting only the distinct ones).

The product of its (nonzero) digits is 9797760, while the sum is 58.

The spelling of 81597636409 in words is "eighty-one billion, five hundred ninety-seven million, six hundred thirty-six thousand, four hundred nine".