21221001221221 has 32 divisors (see below), whose sum is σ = 22505591328768. Its totient is φ = 19980709432320.

The previous prime is 21221001221209. The next prime is 21221001221227. The reversal of 21221001221221 is 12212210012212.

It is a cyclic number.

It is not a de Polignac number, because 21221001221221 - 2¹⁹ = 21221000696933 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221001221227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 214462260 + ... + 214561186.

It is an arithmetic number, because the mean of its divisors is an integer number (703299729024).

Almost surely, 2^{21221001221221} is an apocalyptic number.

It is an amenable number.

21221001221221 is a deficient number, since it is larger than the sum of its proper divisors (1284590107547).

21221001221221 is a wasteful number, since it uses less digits than its factorization.

21221001221221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100101.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21221001221221 its reverse (12212210012212), we get a palindrome (33433211233433).

The spelling of 21221001221221 in words is "twenty-one trillion, two hundred twenty-one billion, one million, two hundred twenty-one thousand, two hundred twenty-one".