21101110111221 has 12 divisors (see below), whose sum is σ = 32728252417632. Its totient is φ = 12057777206328.

The previous prime is 21101110111201. The next prime is 21101110111271. The reversal of 21101110111221 is 12211101110112.

It is not a de Polignac number, because 21101110111221 - 2¹⁷ = 21101109980149 is a prime.

It is a super-2 number, since 2×21101110111221² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21101110111221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101110111201) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 71772483225 + ... + 71772483518.

It is an arithmetic number, because the mean of its divisors is an integer number (2727354368136).

Almost surely, 2^{21101110111221} is an apocalyptic number.

21101110111221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21101110111221 is a deficient number, since it is larger than the sum of its proper divisors (11627142306411).

21101110111221 is a wasteful number, since it uses less digits than its factorization.

21101110111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143544966760 (or 143544966753 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 15.

Adding to 21101110111221 its reverse (12211101110112), we get a palindrome (33312211221333).

The spelling of 21101110111221 in words is "twenty-one trillion, one hundred one billion, one hundred ten million, one hundred eleven thousand, two hundred twenty-one".