123921 has 18 divisors (see below), whose sum is σ = 208962. Its totient is φ = 70560.

The previous prime is 123911. The next prime is 123923. The reversal of 123921 is 129321.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 112896 + 11025 = 336^2 + 105^2 .

It is not a de Polignac number, because 123921 - 2¹⁵ = 91153 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 123894 and 123903.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 123921.

It is not an unprimeable number, because it can be changed into a prime (123923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 301 + ... + 581.

It is an arithmetic number, because the mean of its divisors is an integer number (11609).

2¹²³⁹²¹ is an apocalyptic number.

It is an amenable number.

123921 is a deficient number, since it is larger than the sum of its proper divisors (85041).

123921 is a wasteful number, since it uses less digits than its factorization.

123921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 301 (or 291 counting only the distinct ones).

The product of its digits is 108, while the sum is 18.

The square root of 123921 is about 352.0241468990. The cubic root of 123921 is about 49.8557173843.

The spelling of 123921 in words is "one hundred twenty-three thousand, nine hundred twenty-one".