81809075 has 12 divisors (see below), whose sum is σ = 101556000. Its totient is φ = 65374560.

The previous prime is 81809069. The next prime is 81809149. The reversal of 81809075 is 57090818.

It is not a de Polignac number, because 81809075 - 2¹² = 81804979 is a prime.

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 11 ways as a sum of consecutive naturals, for example, 39926 + ... + 41924.

It is an arithmetic number, because the mean of its divisors is an integer number (8463000).

Almost surely, 2^81809075 is an apocalyptic number.

81809075 is a deficient number, since it is larger than the sum of its proper divisors (19746925).

81809075 is a wasteful number, since it uses less digits than its factorization.

81809075 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3646 (or 3641 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 38.

The square root of 81809075 is about 9044.8369250087. The cubic root of 81809075 is about 434.1107035654.

The spelling of 81809075 in words is "eighty-one million, eight hundred nine thousand, seventy-five".