108921 has 4 divisors (see below), whose sum is σ = 145232. Its totient is φ = 72612.

The previous prime is 108917. The next prime is 108923. The reversal of 108921 is 129801.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 108921 - 2² = 108917 is a prime.

It is a D-number.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 108921.

It is not an unprimeable number, because it can be changed into a prime (108923) 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, 18151 + ... + 18156.

It is an arithmetic number, because the mean of its divisors is an integer number (36308).

2¹⁰⁸⁹²¹ is an apocalyptic number.

It is an amenable number.

108921 is a deficient number, since it is larger than the sum of its proper divisors (36311).

108921 is an equidigital number, since it uses as much as digits as its factorization.

108921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36310.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 108921 is about 330.0318166480. The cubic root of 108921 is about 47.7570186041.

Subtracting from 108921 its sum of digits (21), we obtain a square (108900 = 330²).

The spelling of 108921 in words is "one hundred eight thousand, nine hundred twenty-one".