81172123 has 8 divisors (see below), whose sum is σ = 85709120. Its totient is φ = 76661640.

The previous prime is 81172111. The next prime is 81172139. The reversal of 81172123 is 32127118.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81172123 - 2⁹ = 81171611 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81172103) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 165 + ... + 12742.

It is an arithmetic number, because the mean of its divisors is an integer number (10713640).

Almost surely, 2^81172123 is an apocalyptic number.

81172123 is a deficient number, since it is larger than the sum of its proper divisors (4536997).

81172123 is a wasteful number, since it uses less digits than its factorization.

81172123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13257.

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

The square root of 81172123 is about 9009.5573143191. The cubic root of 81172123 is about 432.9811287372.

The spelling of 81172123 in words is "eighty-one million, one hundred seventy-two thousand, one hundred twenty-three".