21120120 has 288 divisors, whose sum is σ = 86205600. Its totient is φ = 4386816.

The previous prime is 21120119. The next prime is 21120131. The reversal of 21120120 is 2102112.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 728266 + ... + 728294.

It is an arithmetic number, because the mean of its divisors is an integer number (299325).

Almost surely, 2^21120120 is an apocalyptic number.

21120120 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 21120120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43102800).

21120120 is an abundant number, since it is smaller than the sum of its proper divisors (65085480).

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

21120120 is a wasteful number, since it uses less digits than its factorization.

21120120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87 (or 63 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21120120 is about 4595.6631730361. The cubic root of 21120120 is about 276.4174527164.

Adding to 21120120 its reverse (2102112), we get a palindrome (23222232).

The spelling of 21120120 in words is "twenty-one million, one hundred twenty thousand, one hundred twenty".