21122212021221 has 4 divisors (see below), whose sum is σ = 28162949361632. Its totient is φ = 14081474680812.

The previous prime is 21122212021217. The next prime is 21122212021243. The reversal of 21122212021221 is 12212021222112.

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 21122212021221 - 2² = 21122212021217 is a prime.

It is a super-2 number, since 2×21122212021221² (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 (21122212001221) 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, 3520368670201 + ... + 3520368670206.

It is an arithmetic number, because the mean of its divisors is an integer number (7040737340408).

Almost surely, 2^{21122212021221} is an apocalyptic number.

It is an amenable number.

21122212021221 is a deficient number, since it is larger than the sum of its proper divisors (7040737340411).

21122212021221 is an equidigital number, since it uses as much as digits as its factorization.

21122212021221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7040737340410.

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

Adding to 21122212021221 its reverse (12212021222112), we get a palindrome (33334233243333).

The spelling of 21122212021221 in words is "twenty-one trillion, one hundred twenty-two billion, two hundred twelve million, twenty-one thousand, two hundred twenty-one".