21212020100220 has 24 divisors (see below), whose sum is σ = 59393656280784. Its totient is φ = 5656538693376.

The previous prime is 21212020100189. The next prime is 21212020100231. The reversal of 21212020100220 is 2200102021212.

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 21212020100220.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 176766834109 + ... + 176766834228.

It is an arithmetic number, because the mean of its divisors is an integer number (2474735678366).

Almost surely, 2^{21212020100220} is an apocalyptic number.

21212020100220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212020100220 is an abundant number, since it is smaller than the sum of its proper divisors (38181636180564).

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

21212020100220 is a wasteful number, since it uses less digits than its factorization.

21212020100220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 353533668349 (or 353533668347 counting only the distinct ones).

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

Adding to 21212020100220 its reverse (2200102021212), we get a palindrome (23412122121432).

The spelling of 21212020100220 in words is "twenty-one trillion, two hundred twelve billion, twenty million, one hundred thousand, two hundred twenty".