81894071 has 4 divisors (see below), whose sum is σ = 93593232. Its totient is φ = 70194912.

The previous prime is 81894041. The next prime is 81894073. The reversal of 81894071 is 17049818.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17049818 = 2 ⋅8524909.

It is a cyclic number.

It is not a de Polignac number, because 81894071 - 2¹⁰ = 81893047 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 (81894073) 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, 5849570 + ... + 5849583.

It is an arithmetic number, because the mean of its divisors is an integer number (23398308).

Almost surely, 2^81894071 is an apocalyptic number.

81894071 is a deficient number, since it is larger than the sum of its proper divisors (11699161).

81894071 is a wasteful number, since it uses less digits than its factorization.

81894071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11699160.

The product of its (nonzero) digits is 16128, while the sum is 38.

The square root of 81894071 is about 9049.5342974100. The cubic root of 81894071 is about 434.2609921178.

The spelling of 81894071 in words is "eighty-one million, eight hundred ninety-four thousand, seventy-one".