21001022101221 has 16 divisors (see below), whose sum is σ = 28422313382400. Its totient is φ = 13790250519408.

The previous prime is 21001022101177. The next prime is 21001022101259. The reversal of 21001022101221 is 12210122010012.

It is not a de Polignac number, because 21001022101221 - 2¹⁹ = 21001021576933 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21001022101221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001022101921) 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, 3653161 + ... + 7439598.

It is an arithmetic number, because the mean of its divisors is an integer number (1776394586400).

Almost surely, 2^{21001022101221} is an apocalyptic number.

It is an amenable number.

21001022101221 is a deficient number, since it is larger than the sum of its proper divisors (7421291281179).

21001022101221 is a wasteful number, since it uses less digits than its factorization.

21001022101221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11102248.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21001022101221 its reverse (12210122010012), we get a palindrome (33211144111233).

The spelling of 21001022101221 in words is "twenty-one trillion, one billion, twenty-two million, one hundred one thousand, two hundred twenty-one".