21110012220 has 96 divisors (see below), whose sum is σ = 64546707456. Its totient is φ = 5112403200.

The previous prime is 21110012197. The next prime is 21110012239. The reversal of 21110012220 is 2221001112.

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 = 21110012196 and 21110012205.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 658197 + ... + 689523.

It is an arithmetic number, because the mean of its divisors is an integer number (672361536).

Almost surely, 2^21110012220 is an apocalyptic number.

21110012220 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 21110012220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32273353728).

21110012220 is an abundant number, since it is smaller than the sum of its proper divisors (43436695236).

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

21110012220 is a wasteful number, since it uses less digits than its factorization.

21110012220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32371 (or 32369 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21110012220 its reverse (2221001112), we get a palindrome (23331013332).

The spelling of 21110012220 in words is "twenty-one billion, one hundred ten million, twelve thousand, two hundred twenty".