81927896268409 has 3 divisors (see below), whose sum is σ = 81927905319813. Its totient is φ = 81927887217006.

The previous prime is 81927896268397. The next prime is 81927896268433. The reversal of 81927896268409 is 90486269872918.

The square root of 81927896268409 is 9051403.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 81927896268409 - 2¹⁷ = 81927896137337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81927806268409) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4525702 + ... + 13577104.

It is an arithmetic number, because the mean of its divisors is an integer number (27309301773271).

Almost surely, 2^{81927896268409} is an apocalyptic number.

81927896268409 is the 9051403-rd square number.

81927896268409 is the 4525702-nd centered octagonal number.

It is an amenable number.

81927896268409 is a deficient number, since it is larger than the sum of its proper divisors (9051404).

81927896268409 is an frugal number, since it uses more digits than its factorization.

81927896268409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18102806 (or 9051403 counting only the distinct ones).

The product of its (nonzero) digits is 1504935936, while the sum is 79.

The spelling of 81927896268409 in words is "eighty-one trillion, nine hundred twenty-seven billion, eight hundred ninety-six million, two hundred sixty-eight thousand, four hundred nine".