81355123 has 4 divisors (see below), whose sum is σ = 81373320. Its totient is φ = 81336928.

The previous prime is 81355037. The next prime is 81355133. The reversal of 81355123 is 32155318.

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-81355123 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81355091 and 81355100.

It is not an unprimeable number, because it can be changed into a prime (81355133) 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, 2763 + ... + 13051.

It is an arithmetic number, because the mean of its divisors is an integer number (20343330).

Almost surely, 2^81355123 is an apocalyptic number.

81355123 is a deficient number, since it is larger than the sum of its proper divisors (18197).

81355123 is a wasteful number, since it uses less digits than its factorization.

81355123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18196.

The product of its digits is 3600, while the sum is 28.

The square root of 81355123 is about 9019.7074786270. The cubic root of 81355123 is about 433.3062653046.

The spelling of 81355123 in words is "eighty-one million, three hundred fifty-five thousand, one hundred twenty-three".