21212221101021 has 24 divisors (see below), whose sum is σ = 30709824088320. Its totient is φ = 14109232134816.

The previous prime is 21212221100971. The next prime is 21212221101077. The reversal of 21212221101021 is 12010112221212.

It is a de Polignac number, because none of the positive numbers 2^k-21212221101021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21212221100985 and 21212221101003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212221101091) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5664700 + ... + 8632106.

It is an arithmetic number, because the mean of its divisors is an integer number (1279576003680).

Almost surely, 2^{21212221101021} is an apocalyptic number.

It is an amenable number.

21212221101021 is a deficient number, since it is larger than the sum of its proper divisors (9497602987299).

21212221101021 is a wasteful number, since it uses less digits than its factorization.

21212221101021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2969225 (or 2969222 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21212221101021 its reverse (12010112221212), we get a palindrome (33222333322233).

The spelling of 21212221101021 in words is "twenty-one trillion, two hundred twelve billion, two hundred twenty-one million, one hundred one thousand, twenty-one".