81444113 has 4 divisors (see below), whose sum is σ = 81463860. Its totient is φ = 81424368.

The previous prime is 81444109. The next prime is 81444137. The reversal of 81444113 is 31144418.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31144418 = 2 ⋅15572209.

It can be written as a sum of positive squares in 2 ways, for example, as 6932689 + 74511424 = 2633^2 + 8632^2 .

It is a cyclic number.

It is not a de Polignac number, because 81444113 - 2² = 81444109 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81444413) 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, 1070 + ... + 12807.

It is an arithmetic number, because the mean of its divisors is an integer number (20365965).

Almost surely, 2^81444113 is an apocalyptic number.

It is an amenable number.

81444113 is a deficient number, since it is larger than the sum of its proper divisors (19747).

81444113 is a wasteful number, since it uses less digits than its factorization.

81444113 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19746.

The product of its digits is 1536, while the sum is 26.

The square root of 81444113 is about 9024.6392171654. The cubic root of 81444113 is about 433.4641978852.

The spelling of 81444113 in words is "eighty-one million, four hundred forty-four thousand, one hundred thirteen".