21221012221212 has 48 divisors (see below), whose sum is σ = 51680440318752. Its totient is φ = 6770931947520.

The previous prime is 21221012221169. The next prime is 21221012221229. The reversal of 21221012221212 is 21212221012212.

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, 406880893 + ... + 406933044.

It is an arithmetic number, because the mean of its divisors is an integer number (1076675839974).

Almost surely, 2^{21221012221212} is an apocalyptic number.

It is an amenable number.

21221012221212 is an abundant number, since it is smaller than the sum of its proper divisors (30459428097540).

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

21221012221212 is a wasteful number, since it uses less digits than its factorization.

21221012221212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 813814038 (or 813814036 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

Adding to 21221012221212 its reverse (21212221012212), we get a palindrome (42433233233424).

The spelling of 21221012221212 in words is "twenty-one trillion, two hundred twenty-one billion, twelve million, two hundred twenty-one thousand, two hundred twelve".