21101111220 has 48 divisors (see below), whose sum is σ = 67523557248. Its totient is φ = 4823111040.

The previous prime is 21101111189. The next prime is 21101111221. The reversal of 21101111220 is 2211110112.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21101111196 and 21101111205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101111221) 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, 25119951 + ... + 25120790.

It is an arithmetic number, because the mean of its divisors is an integer number (1406740776).

Almost surely, 2^21101111220 is an apocalyptic number.

21101111220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21101111220 is an abundant number, since it is smaller than the sum of its proper divisors (46422446028).

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

21101111220 is a wasteful number, since it uses less digits than its factorization.

21101111220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50240760 (or 50240758 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21101111220 its reverse (2211110112), we get a palindrome (23312221332).

The spelling of 21101111220 in words is "twenty-one billion, one hundred one million, one hundred eleven thousand, two hundred twenty".