21001022220221 has 16 divisors (see below), whose sum is σ = 22319857627200. Its totient is φ = 19703653947648.

The previous prime is 21001022220197. The next prime is 21001022220247. The reversal of 21001022220221 is 12202222010012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21001022220221 - 2²² = 21001018025917 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21001022220221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001022229221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4964981 + ... + 8164133.

It is an arithmetic number, because the mean of its divisors is an integer number (1394991101700).

Almost surely, 2^{21001022220221} is an apocalyptic number.

It is an amenable number.

21001022220221 is a deficient number, since it is larger than the sum of its proper divisors (1318835406979).

21001022220221 is a wasteful number, since it uses less digits than its factorization.

21001022220221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3202508.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21001022220221 its reverse (12202222010012), we get a palindrome (33203244230233).

The spelling of 21001022220221 in words is "twenty-one trillion, one billion, twenty-two million, two hundred twenty thousand, two hundred twenty-one".