81661694 has 8 divisors (see below), whose sum is σ = 122637720. Its totient is φ = 40782456.

The previous prime is 81661673. The next prime is 81661703. The reversal of 81661694 is 49616618.

It is a sphenic number, since it is the product of 3 distinct primes.

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, 22049 + ... + 25484.

It is an arithmetic number, because the mean of its divisors is an integer number (15329715).

Almost surely, 2^81661694 is an apocalyptic number.

81661694 is a deficient number, since it is larger than the sum of its proper divisors (40976026).

81661694 is a wasteful number, since it uses less digits than its factorization.

81661694 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48394.

The product of its digits is 62208, while the sum is 41.

The square root of 81661694 is about 9036.6860076026. The cubic root of 81661694 is about 433.8498599348.

The spelling of 81661694 in words is "eighty-one million, six hundred sixty-one thousand, six hundred ninety-four".