21100120 has 32 divisors (see below), whose sum is σ = 48016800. Its totient is φ = 8343808.

The previous prime is 21100103. The next prime is 21100129. The reversal of 21100120 is 2100112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100129) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 597 + ... + 6523.

It is an arithmetic number, because the mean of its divisors is an integer number (1500525).

Almost surely, 2^21100120 is an apocalyptic number.

21100120 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 21100120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24008400).

21100120 is an abundant number, since it is smaller than the sum of its proper divisors (26916680).

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

21100120 is a wasteful number, since it uses less digits than its factorization.

21100120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6027 (or 6023 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 21100120 is about 4593.4866931341. The cubic root of 21100120 is about 276.3301726721.

Adding to 21100120 its reverse (2100112), we get a palindrome (23200232).

The spelling of 21100120 in words is "twenty-one million, one hundred thousand, one hundred twenty".