21121110112221 has 24 divisors (see below), whose sum is σ = 34867838241600. Its totient is φ = 12068775242496.

The previous prime is 21121110112189. The next prime is 21121110112273. The reversal of 21121110112221 is 12221101112112.

It is a happy number.

21121110112221 is a `hidden beast` number, since 211 + 211 + 10 + 1 + 12 + 221 = 666.

It is not a de Polignac number, because 21121110112221 - 2⁵ = 21121110112189 is a prime.

It is a super-2 number, since 2×21121110112221² (a number of 27 digits) contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21121110112194 and 21121110112203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121110112021) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4195380 + ... + 7735853.

It is an arithmetic number, because the mean of its divisors is an integer number (1452826593400).

Almost surely, 2^{21121110112221} is an apocalyptic number.

21121110112221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21121110112221 is a deficient number, since it is larger than the sum of its proper divisors (13746728129379).

21121110112221 is a wasteful number, since it uses less digits than its factorization.

21121110112221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11959345 (or 11959342 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 18.

Adding to 21121110112221 its reverse (12221101112112), we get a palindrome (33342211224333).

The spelling of 21121110112221 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred ten million, one hundred twelve thousand, two hundred twenty-one".