81840231 has 12 divisors (see below), whose sum is σ = 128960520. Its totient is φ = 49600080.

The previous prime is 81840229. The next prime is 81840251. The reversal of 81840231 is 13204818.

It is not a de Polignac number, because 81840231 - 2¹ = 81840229 is a prime.

It is a super-2 number, since 2×81840231² = 13395646820266722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81840195 and 81840204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81840211) 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, 413236 + ... + 413433.

It is an arithmetic number, because the mean of its divisors is an integer number (10746710).

Almost surely, 2^81840231 is an apocalyptic number.

81840231 is a deficient number, since it is larger than the sum of its proper divisors (47120289).

81840231 is a wasteful number, since it uses less digits than its factorization.

81840231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 826686 (or 826683 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 81840231 is about 9046.5590696132. The cubic root of 81840231 is about 434.1658051804.

The spelling of 81840231 in words is "eighty-one million, eight hundred forty thousand, two hundred thirty-one".