81823931 has 4 divisors (see below), whose sum is σ = 93513072. Its totient is φ = 70134792.

The previous prime is 81823927. The next prime is 81823939. The reversal of 81823931 is 13932818.

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

It is not a de Polignac number, because 81823931 - 2² = 81823927 is a prime.

It is a super-2 number, since 2×81823931² = 13390311368585522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81823891 and 81823900.

It is not an unprimeable number, because it can be changed into a prime (81823939) 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, 5844560 + ... + 5844573.

It is an arithmetic number, because the mean of its divisors is an integer number (23378268).

Almost surely, 2^81823931 is an apocalyptic number.

81823931 is a deficient number, since it is larger than the sum of its proper divisors (11689141).

81823931 is a wasteful number, since it uses less digits than its factorization.

81823931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11689140.

The product of its digits is 10368, while the sum is 35.

The square root of 81823931 is about 9045.6581297327. The cubic root of 81823931 is about 434.1369792089.

The spelling of 81823931 in words is "eighty-one million, eight hundred twenty-three thousand, nine hundred thirty-one".