21212021012220 has 288 divisors, whose sum is σ = 69672024414720. Its totient is φ = 5407130868480.

The previous prime is 21212021012219. The next prime is 21212021012291. The reversal of 21212021012220 is 2221012021212.

It is a happy number.

21212021012220 is a `hidden beast` number, since 21 + 212 + 0 + 210 + 1 + 2 + 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 = 21212021012193 and 21212021012202.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 176440530 + ... + 176560710.

It is an arithmetic number, because the mean of its divisors is an integer number (241916751440).

Almost surely, 2^{21212021012220} is an apocalyptic number.

21212021012220 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 21212021012220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34836012207360).

21212021012220 is an abundant number, since it is smaller than the sum of its proper divisors (48460003402500).

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

21212021012220 is a wasteful number, since it uses less digits than its factorization.

21212021012220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121807 (or 121793 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21212021012220 its reverse (2221012021212), we get a palindrome (23433033033432).

The spelling of 21212021012220 in words is "twenty-one trillion, two hundred twelve billion, twenty-one million, twelve thousand, two hundred twenty".