81894631 has 12 divisors (see below), whose sum is σ = 102594072. Its totient is φ = 64795248.

The previous prime is 81894611. The next prime is 81894641. The reversal of 81894631 is 13649818.

It is not a de Polignac number, because 81894631 - 2⁵ = 81894599 is a prime.

It is a super-2 number, since 2×81894631² = 13413461173252322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81894611) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 63645 + ... + 64918.

It is an arithmetic number, because the mean of its divisors is an integer number (8549506).

Almost surely, 2^81894631 is an apocalyptic number.

81894631 is a deficient number, since it is larger than the sum of its proper divisors (20699441).

81894631 is a wasteful number, since it uses less digits than its factorization.

81894631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128590 (or 128583 counting only the distinct ones).

The product of its digits is 41472, while the sum is 40.

The square root of 81894631 is about 9049.5652381758. The cubic root of 81894631 is about 434.2619819559.

The spelling of 81894631 in words is "eighty-one million, eight hundred ninety-four thousand, six hundred thirty-one".