81516554579 has 4 divisors (see below), whose sum is σ = 81517149384. Its totient is φ = 81515959776.

The previous prime is 81516554543. The next prime is 81516554597. The reversal of 81516554579 is 97545561518.

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 a cyclic number.

It is not a de Polignac number, because 81516554579 - 2⁸ = 81516554323 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81516554179) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23819 + ... + 404475.

It is an arithmetic number, because the mean of its divisors is an integer number (20379287346).

Almost surely, 2^81516554579 is an apocalyptic number.

81516554579 is a deficient number, since it is larger than the sum of its proper divisors (594805).

81516554579 is a wasteful number, since it uses less digits than its factorization.

81516554579 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 594804.

The product of its digits is 7560000, while the sum is 56.

The spelling of 81516554579 in words is "eighty-one billion, five hundred sixteen million, five hundred fifty-four thousand, five hundred seventy-nine".