81659394 has 32 divisors (see below), whose sum is σ = 187322880. Its totient is φ = 26341200.

The previous prime is 81659387. The next prime is 81659411. The reversal of 81659394 is 49395618.

It is a happy number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22717 + ... + 26064.

It is an arithmetic number, because the mean of its divisors is an integer number (5853840).

Almost surely, 2^81659394 is an apocalyptic number.

81659394 is an abundant number, since it is smaller than the sum of its proper divisors (105663486).

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

81659394 is a wasteful number, since it uses less digits than its factorization.

81659394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48823 (or 48817 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The square root of 81659394 is about 9036.5587476650. The cubic root of 81659394 is about 433.8457867723.

The spelling of 81659394 in words is "eighty-one million, six hundred fifty-nine thousand, three hundred ninety-four".