21001101111221 has 36 divisors (see below), whose sum is σ = 26863934078016. Its totient is φ = 16357616185680.

The previous prime is 21001101111209. The next prime is 21001101111229. The reversal of 21001101111221 is 12211110110012.

It is a de Polignac number, because none of the positive numbers 2^k-21001101111221 is a prime.

It is a super-2 number, since 2×21001101111221² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21001101111196 and 21001101111205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001101111229) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 13385606 + ... + 14872008.

It is an arithmetic number, because the mean of its divisors is an integer number (746220391056).

Almost surely, 2^{21001101111221} is an apocalyptic number.

It is an amenable number.

21001101111221 is a deficient number, since it is larger than the sum of its proper divisors (5862832966795).

21001101111221 is a wasteful number, since it uses less digits than its factorization.

21001101111221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1488822 (or 1488804 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 14.

Adding to 21001101111221 its reverse (12211110110012), we get a palindrome (33212211221233).

The spelling of 21001101111221 in words is "twenty-one trillion, one billion, one hundred one million, one hundred eleven thousand, two hundred twenty-one".