21955120 has 80 divisors (see below), whose sum is σ = 56737440. Its totient is φ = 7833600.

The previous prime is 21955093. The next prime is 21955121. The reversal of 21955120 is 2155912.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (21955121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 53476 + ... + 53884.

It is an arithmetic number, because the mean of its divisors is an integer number (709218).

Almost surely, 2^21955120 is an apocalyptic number.

21955120 is a gapful number since it is divisible by the number (20) 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 21955120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28368720).

21955120 is an abundant number, since it is smaller than the sum of its proper divisors (34782320).

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

21955120 is a wasteful number, since it uses less digits than its factorization.

21955120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 494 (or 488 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 21955120 is about 4685.6290933022. The cubic root of 21955120 is about 280.0132646777.

The spelling of 21955120 in words is "twenty-one million, nine hundred fifty-five thousand, one hundred twenty".