81694 has 4 divisors (see below), whose sum is σ = 122544. Its totient is φ = 40846.

The previous prime is 81689. The next prime is 81701. The reversal of 81694 is 49618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 49618 = 2 ⋅24809.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 20422 + ... + 20425.

It is an arithmetic number, because the mean of its divisors is an integer number (30636).

2⁸¹⁶⁹⁴ is an apocalyptic number.

81694 is a deficient number, since it is larger than the sum of its proper divisors (40850).

81694 is a wasteful number, since it uses less digits than its factorization.

81694 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40849.

The product of its digits is 1728, while the sum is 28.

The square root of 81694 is about 285.8216226950. The cubic root of 81694 is about 43.3907063849.

The spelling of 81694 in words is "eighty-one thousand, six hundred ninety-four".