81175815 has 48 divisors (see below), whose sum is σ = 164256768. Its totient is φ = 36312768.

The previous prime is 81175769. The next prime is 81175837. The reversal of 81175815 is 51857118.

It is a happy number.

It is not a de Polignac number, because 81175815 - 2⁸ = 81175559 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81175815.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 12064 + ... + 17546.

It is an arithmetic number, because the mean of its divisors is an integer number (3422016).

Almost surely, 2^81175815 is an apocalyptic number.

81175815 is an abundant number, since it is smaller than the sum of its proper divisors (83080953).

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

81175815 is a wasteful number, since it uses less digits than its factorization.

81175815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5548 (or 5545 counting only the distinct ones).

The product of its digits is 11200, while the sum is 36.

The square root of 81175815 is about 9009.7622055191. The cubic root of 81175815 is about 432.9876931505.

The spelling of 81175815 in words is "eighty-one million, one hundred seventy-five thousand, eight hundred fifteen".