21101212120 has 64 divisors (see below), whose sum is σ = 48518870400. Its totient is φ = 8255623680.

The previous prime is 21101212103. The next prime is 21101212123. The reversal of 21101212120 is 2121210112.

It is a super-2 number, since 2×21101212120² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21101212120.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101212123) 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, 4338490 + ... + 4343350.

It is an arithmetic number, because the mean of its divisors is an integer number (758107350).

Almost surely, 2^21101212120 is an apocalyptic number.

21101212120 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 21101212120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24259435200).

21101212120 is an abundant number, since it is smaller than the sum of its proper divisors (27417658280).

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

21101212120 is a wasteful number, since it uses less digits than its factorization.

21101212120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7228 (or 7224 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21101212120 its reverse (2121210112), we get a palindrome (23222422232).

The spelling of 21101212120 in words is "twenty-one billion, one hundred one million, two hundred twelve thousand, one hundred twenty".