21212111012220 has 144 divisors (see below), whose sum is σ = 68490909396000. Its totient is φ = 5298637234176.

The previous prime is 21212111012207. The next prime is 21212111012237. The reversal of 21212111012220 is 2221011121212.

21212111012220 is a `hidden beast` number, since 212 + 1 + 211 + 10 + 12 + 220 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21212111012193 and 21212111012202.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 34540405 + ... + 35149164.

It is an arithmetic number, because the mean of its divisors is an integer number (475631315250).

Almost surely, 2^{21212111012220} is an apocalyptic number.

21212111012220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212111012220 is an abundant number, since it is smaller than the sum of its proper divisors (47278798383780).

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

21212111012220 is a wasteful number, since it uses less digits than its factorization.

21212111012220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69689692 (or 69689687 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21212111012220 its reverse (2221011121212), we get a palindrome (23433122133432).

The spelling of 21212111012220 in words is "twenty-one trillion, two hundred twelve billion, one hundred eleven million, twelve thousand, two hundred twenty".