81394693 has 4 divisors (see below), whose sum is σ = 81416160. Its totient is φ = 81373228.

The previous prime is 81394669. The next prime is 81394721. The reversal of 81394693 is 39649318.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 39649318 = 2 ⋅19824659.

It is a cyclic number.

It is not a de Polignac number, because 81394693 - 2⁵ = 81394661 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 (81394633) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3355 + ... + 13192.

It is an arithmetic number, because the mean of its divisors is an integer number (20354040).

Almost surely, 2^81394693 is an apocalyptic number.

It is an amenable number.

81394693 is a deficient number, since it is larger than the sum of its proper divisors (21467).

81394693 is a wasteful number, since it uses less digits than its factorization.

81394693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21466.

The product of its digits is 139968, while the sum is 43.

The square root of 81394693 is about 9021.9007420831. The cubic root of 81394693 is about 433.3765052977.

The spelling of 81394693 in words is "eighty-one million, three hundred ninety-four thousand, six hundred ninety-three".