81694639 has 8 divisors (see below), whose sum is σ = 93154320. Its totient is φ = 70974336.

The previous prime is 81694637. The next prime is 81694649. The reversal of 81694639 is 93649618.

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

It is a cyclic number.

It is not a de Polignac number, because 81694639 - 2¹ = 81694637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81694637) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 184609 + ... + 185050.

It is an arithmetic number, because the mean of its divisors is an integer number (11644290).

Almost surely, 2^81694639 is an apocalyptic number.

81694639 is a deficient number, since it is larger than the sum of its proper divisors (11459681).

81694639 is a wasteful number, since it uses less digits than its factorization.

81694639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 369689.

The product of its digits is 279936, while the sum is 46.

The square root of 81694639 is about 9038.5086712355. The cubic root of 81694639 is about 433.9081951683.

The spelling of 81694639 in words is "eighty-one million, six hundred ninety-four thousand, six hundred thirty-nine".