21212012211220 has 48 divisors (see below), whose sum is σ = 45045040456080. Its totient is φ = 8389759832064.

The previous prime is 21212012211191. The next prime is 21212012211233. The reversal of 21212012211220 is 2211221021212.

It can be written as a sum of positive squares in 8 ways, for example, as 7480629785476 + 13731382425744 = 2735074^2 + 3705588^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2778219 + ... + 7081138.

It is an arithmetic number, because the mean of its divisors is an integer number (938438342835).

Almost surely, 2^{21212012211220} is an apocalyptic number.

21212012211220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212012211220 is an abundant number, since it is smaller than the sum of its proper divisors (23833028244860).

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

21212012211220 is a wasteful number, since it uses less digits than its factorization.

21212012211220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9860572 (or 9860570 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21212012211220 its reverse (2211221021212), we get a palindrome (23423233232432).

The spelling of 21212012211220 in words is "twenty-one trillion, two hundred twelve billion, twelve million, two hundred eleven thousand, two hundred twenty".