81697255523 has 4 divisors (see below), whose sum is σ = 87981659808. Its totient is φ = 75412851240.

The previous prime is 81697255511. The next prime is 81697255529. The reversal of 81697255523 is 32555279618.

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

It is a cyclic number.

It is not a de Polignac number, because 81697255523 - 2²⁶ = 81630146659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81697255529) 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, 3142202123 + ... + 3142202148.

It is an arithmetic number, because the mean of its divisors is an integer number (21995414952).

Almost surely, 2^81697255523 is an apocalyptic number.

81697255523 is a deficient number, since it is larger than the sum of its proper divisors (6284404285).

81697255523 is a wasteful number, since it uses less digits than its factorization.

81697255523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6284404284.

The product of its digits is 4536000, while the sum is 53.

The spelling of 81697255523 in words is "eighty-one billion, six hundred ninety-seven million, two hundred fifty-five thousand, five hundred twenty-three".