81518172 has 12 divisors (see below), whose sum is σ = 190209096. Its totient is φ = 27172720.

The previous prime is 81518149. The next prime is 81518183. The reversal of 81518172 is 27181518.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3396579 + ... + 3396602.

It is an arithmetic number, because the mean of its divisors is an integer number (15850758).

Almost surely, 2^81518172 is an apocalyptic number.

It is an amenable number.

81518172 is an abundant number, since it is smaller than the sum of its proper divisors (108690924).

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

81518172 is a wasteful number, since it uses less digits than its factorization.

81518172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6793188 (or 6793186 counting only the distinct ones).

The product of its digits is 4480, while the sum is 33.

The square root of 81518172 is about 9028.7414405331. The cubic root of 81518172 is about 433.5955443935.

The spelling of 81518172 in words is "eighty-one million, five hundred eighteen thousand, one hundred seventy-two".