81863 has 4 divisors (see below), whose sum is σ = 83088. Its totient is φ = 80640.

The previous prime is 81853. The next prime is 81869. The reversal of 81863 is 36818.

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

It is a cyclic number.

It is not a de Polignac number, because 81863 - 2⁴ = 81847 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 (81869) 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, 506 + ... + 647.

It is an arithmetic number, because the mean of its divisors is an integer number (20772).

2⁸¹⁸⁶³ is an apocalyptic number.

81863 is a deficient number, since it is larger than the sum of its proper divisors (1225).

81863 is a wasteful number, since it uses less digits than its factorization.

81863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1224.

The product of its digits is 1152, while the sum is 26.

The square root of 81863 is about 286.1171088907. The cubic root of 81863 is about 43.4206064942.

The spelling of 81863 in words is "eighty-one thousand, eight hundred sixty-three".