81623 has 4 divisors (see below), whose sum is σ = 84288. Its totient is φ = 78960.

The previous prime is 81619. The next prime is 81629. The reversal of 81623 is 32618.

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 81623 - 2² = 81619 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81595 and 81604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81629) 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, 1286 + ... + 1347.

It is an arithmetic number, because the mean of its divisors is an integer number (21072).

2⁸¹⁶²³ is an apocalyptic number.

81623 is a deficient number, since it is larger than the sum of its proper divisors (2665).

81623 is a wasteful number, since it uses less digits than its factorization.

81623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2664.

The product of its digits is 288, while the sum is 20.

The square root of 81623 is about 285.6973923577. The cubic root of 81623 is about 43.3781324992.

The spelling of 81623 in words is "eighty-one thousand, six hundred twenty-three".