81123456172 has 48 divisors (see below), whose sum is σ = 166814524800. Its totient is φ = 34121122560.

The previous prime is 81123456097. The next prime is 81123456181. The reversal of 81123456172 is 27165432118.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1092397 + ... + 1164292.

It is an arithmetic number, because the mean of its divisors is an integer number (3475302600).

Almost surely, 2^81123456172 is an apocalyptic number.

It is an amenable number.

81123456172 is an abundant number, since it is smaller than the sum of its proper divisors (85691068628).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81123456172 is a wasteful number, since it uses less digits than its factorization.

81123456172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2256766 (or 2256764 counting only the distinct ones).

The product of its digits is 80640, while the sum is 40.

The spelling of 81123456172 in words is "eighty-one billion, one hundred twenty-three million, four hundred fifty-six thousand, one hundred seventy-two".