81144870617 has 4 divisors (see below), whose sum is σ = 81162352080. Its totient is φ = 81127389156.

The previous prime is 81144870613. The next prime is 81144870629. The reversal of 81144870617 is 71607844118.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81144870617 - 2² = 81144870613 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81144870613) 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, 8733767 + ... + 8743052.

It is an arithmetic number, because the mean of its divisors is an integer number (20290588020).

Almost surely, 2^81144870617 is an apocalyptic number.

It is an amenable number.

81144870617 is a deficient number, since it is larger than the sum of its proper divisors (17481463).

81144870617 is a wasteful number, since it uses less digits than its factorization.

81144870617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17481462.

The product of its (nonzero) digits is 301056, while the sum is 47.

The spelling of 81144870617 in words is "eighty-one billion, one hundred forty-four million, eight hundred seventy thousand, six hundred seventeen".