1221920 has 48 divisors (see below), whose sum is σ = 3302208. Its totient is φ = 418560.

The previous prime is 1221917. The next prime is 1221937. The reversal of 1221920 is 291221.

It is an unprimeable number.

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, 575 + ... + 1665.

It is an arithmetic number, because the mean of its divisors is an integer number (68796).

2^1221920 is an apocalyptic number.

1221920 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 1221920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1651104).

1221920 is an abundant number, since it is smaller than the sum of its proper divisors (2080288).

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

1221920 is a wasteful number, since it uses less digits than its factorization.

1221920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1113 (or 1105 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 1221920 is about 1105.4049031916. The cubic root of 1221920 is about 106.9089976538.

The spelling of 1221920 in words is "one million, two hundred twenty-one thousand, nine hundred twenty".