121920 has 56 divisors (see below), whose sum is σ = 390144. Its totient is φ = 32256.

The previous prime is 121909. The next prime is 121921. The reversal of 121920 is 29121.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 121920.

It is not an unprimeable number, because it can be changed into a prime (121921) 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 7 ways as a sum of consecutive naturals, for example, 897 + ... + 1023.

2¹²¹⁹²⁰ is an apocalyptic number.

121920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 121920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (195072).

121920 is an abundant number, since it is smaller than the sum of its proper divisors (268224).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

121920 is a wasteful number, since it uses less digits than its factorization.

121920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147 (or 137 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 121920 is about 349.1704454847. The cubic root of 121920 is about 49.5859134469.

121920 divided by its sum of digits (15) gives a triangular number (8128 = T₁₂₇).

The spelling of 121920 in words is "one hundred twenty-one thousand, nine hundred twenty".