81123573878 has 16 divisors (see below), whose sum is σ = 130474255680. Its totient is φ = 37692560256.

The previous prime is 81123573847. The next prime is 81123573887. The reversal of 81123573878 is 87837532118.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15098501 + ... + 15103872.

It is an arithmetic number, because the mean of its divisors is an integer number (8154640980).

Almost surely, 2^81123573878 is an apocalyptic number.

81123573878 is a deficient number, since it is larger than the sum of its proper divisors (49350681802).

81123573878 is a wasteful number, since it uses less digits than its factorization.

81123573878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30202471.

The product of its digits is 2257920, while the sum is 53.

The spelling of 81123573878 in words is "eighty-one billion, one hundred twenty-three million, five hundred seventy-three thousand, eight hundred seventy-eight".