81121457023 has 4 divisors (see below), whose sum is σ = 81134900440. Its totient is φ = 81108013608.

The previous prime is 81121457003. The next prime is 81121457047. The reversal of 81121457023 is 32075412118.

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-81121457023 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81121457023.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81121457003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6712653 + ... + 6724726.

It is an arithmetic number, because the mean of its divisors is an integer number (20283725110).

Almost surely, 2^81121457023 is an apocalyptic number.

81121457023 is a deficient number, since it is larger than the sum of its proper divisors (13443417).

81121457023 is a wasteful number, since it uses less digits than its factorization.

81121457023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13443416.

The product of its (nonzero) digits is 13440, while the sum is 34.

The spelling of 81121457023 in words is "eighty-one billion, one hundred twenty-one million, four hundred fifty-seven thousand, twenty-three".