21212102220 has 96 divisors (see below), whose sum is σ = 61592014848. Its totient is φ = 5450188032.

The previous prime is 21212102201. The next prime is 21212102237. The reversal of 21212102220 is 2220121212.

It is a super-3 number, since 3×21212102220³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21212102220.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 182277 + ... + 275043.

It is an arithmetic number, because the mean of its divisors is an integer number (641583488).

Almost surely, 2^21212102220 is an apocalyptic number.

21212102220 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 21212102220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30796007424).

21212102220 is an abundant number, since it is smaller than the sum of its proper divisors (40379912628).

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

21212102220 is a wasteful number, since it uses less digits than its factorization.

21212102220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92919 (or 92917 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21212102220 its reverse (2220121212), we get a palindrome (23432223432).

The spelling of 21212102220 in words is "twenty-one billion, two hundred twelve million, one hundred two thousand, two hundred twenty".