21221221122021 has 4 divisors (see below), whose sum is σ = 28294961496032. Its totient is φ = 14147480748012.

The previous prime is 21221221122011. The next prime is 21221221122067. The reversal of 21221221122021 is 12022112212212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21221221122021 - 2¹⁰ = 21221221120997 is a prime.

It is a super-2 number, since 2×21221221122021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221221122011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3536870187001 + ... + 3536870187006.

It is an arithmetic number, because the mean of its divisors is an integer number (7073740374008).

Almost surely, 2^{21221221122021} is an apocalyptic number.

It is an amenable number.

21221221122021 is a deficient number, since it is larger than the sum of its proper divisors (7073740374011).

21221221122021 is an equidigital number, since it uses as much as digits as its factorization.

21221221122021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7073740374010.

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

Adding to 21221221122021 its reverse (12022112212212), we get a palindrome (33243333334233).

The spelling of 21221221122021 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty-one million, one hundred twenty-two thousand, twenty-one".