21222220221221 has 8 divisors (see below), whose sum is σ = 21684595476600. Its totient is φ = 20762139632832.

The previous prime is 21222220221179. The next prime is 21222220221233. The reversal of 21222220221221 is 12212202222212.

It can be written as a sum of positive squares in 4 ways, for example, as 8731374912100 + 12490845309121 = 2954890^2 + 3534239^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21222220221221 - 2¹⁴ = 21222220204837 is a prime.

It is a super-2 number, since 2×21222220221221² (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 (21222220224221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 573648050 + ... + 573685043.

It is an arithmetic number, because the mean of its divisors is an integer number (2710574434575).

Almost surely, 2^{21222220221221} is an apocalyptic number.

It is an amenable number.

21222220221221 is a deficient number, since it is larger than the sum of its proper divisors (462375255379).

21222220221221 is a wasteful number, since it uses less digits than its factorization.

21222220221221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1147333495.

The product of its (nonzero) digits is 1024, while the sum is 23.

Adding to 21222220221221 its reverse (12212202222212), we get a palindrome (33434422443433).

The spelling of 21222220221221 in words is "twenty-one trillion, two hundred twenty-two billion, two hundred twenty million, two hundred twenty-one thousand, two hundred twenty-one".