81817875 has 24 divisors (see below), whose sum is σ = 147492384. Its totient is φ = 43635600.

The previous prime is 81817873. The next prime is 81817913. The reversal of 81817875 is 57871818.

It is not a de Polignac number, because 81817875 - 2¹ = 81817873 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 81817875.

It is not an unprimeable number, because it can be changed into a prime (81817873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 35239 + ... + 37488.

It is an arithmetic number, because the mean of its divisors is an integer number (6145516).

Almost surely, 2^81817875 is an apocalyptic number.

81817875 is a deficient number, since it is larger than the sum of its proper divisors (65674509).

81817875 is a wasteful number, since it uses less digits than its factorization.

81817875 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72748 (or 72735 counting only the distinct ones).

The product of its digits is 125440, while the sum is 45.

The square root of 81817875 is about 9045.3233773039. The cubic root of 81817875 is about 434.1262684124.

The spelling of 81817875 in words is "eighty-one million, eight hundred seventeen thousand, eight hundred seventy-five".