81125415823 has 4 divisors (see below), whose sum is σ = 81192965248. Its totient is φ = 81057866400.

The previous prime is 81125415809. The next prime is 81125415829. The reversal of 81125415823 is 32851452118.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81125415823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81125415829) 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, 33772911 + ... + 33775312.

It is an arithmetic number, because the mean of its divisors is an integer number (20298241312).

Almost surely, 2^81125415823 is an apocalyptic number.

81125415823 is a deficient number, since it is larger than the sum of its proper divisors (67549425).

81125415823 is a wasteful number, since it uses less digits than its factorization.

81125415823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67549424.

The product of its digits is 76800, while the sum is 40.

The spelling of 81125415823 in words is "eighty-one billion, one hundred twenty-five million, four hundred fifteen thousand, eight hundred twenty-three".