81694523 has 4 divisors (see below), whose sum is σ = 81735720. Its totient is φ = 81653328.

The previous prime is 81694513. The next prime is 81694541. The reversal of 81694523 is 32549618.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81694523 - 2²² = 77500219 is a prime.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81694513) by changing a digit.

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, 17465 + ... + 21642.

It is an arithmetic number, because the mean of its divisors is an integer number (20433930).

Almost surely, 2^81694523 is an apocalyptic number.

81694523 is a deficient number, since it is larger than the sum of its proper divisors (41197).

81694523 is a wasteful number, since it uses less digits than its factorization.

81694523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41196.

The product of its digits is 51840, while the sum is 38.

The square root of 81694523 is about 9038.5022542454. The cubic root of 81694523 is about 433.9079897963.

The spelling of 81694523 in words is "eighty-one million, six hundred ninety-four thousand, five hundred twenty-three".