81123172 has 24 divisors (see below), whose sum is σ = 153139896. Its totient is φ = 37379328.

The previous prime is 81123157. The next prime is 81123181. The reversal of 81123172 is 27132118.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1806336 + 79316836 = 1344^2 + 8906^2 .

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, 48738 + ... + 50374.

It is an arithmetic number, because the mean of its divisors is an integer number (6380829).

Almost surely, 2^81123172 is an apocalyptic number.

It is an amenable number.

81123172 is a deficient number, since it is larger than the sum of its proper divisors (72016724).

81123172 is a wasteful number, since it uses less digits than its factorization.

81123172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2607 (or 2605 counting only the distinct ones).

The product of its digits is 672, while the sum is 25.

The square root of 81123172 is about 9006.8402894689. The cubic root of 81123172 is about 432.8940745433.

The spelling of 81123172 in words is "eighty-one million, one hundred twenty-three thousand, one hundred seventy-two".