21201212221221 has 8 divisors (see below), whose sum is σ = 28268318629440. Its totient is φ = 14134123646912.

The previous prime is 21201212221213. The next prime is 21201212221303. The reversal of 21201212221221 is 12212221210212.

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 21201212221221 - 2³ = 21201212221213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201212221621) 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, 1381140 + ... + 6656573.

It is an arithmetic number, because the mean of its divisors is an integer number (3533539828680).

Almost surely, 2^{21201212221221} is an apocalyptic number.

It is an amenable number.

21201212221221 is a deficient number, since it is larger than the sum of its proper divisors (7067106408219).

21201212221221 is an equidigital number, since it uses as much as digits as its factorization.

21201212221221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8916955.

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

Adding to 21201212221221 its reverse (12212221210212), we get a palindrome (33413433431433).

The spelling of 21201212221221 in words is "twenty-one trillion, two hundred one billion, two hundred twelve million, two hundred twenty-one thousand, two hundred twenty-one".