21210121111221 has 48 divisors (see below), whose sum is σ = 37440213977088. Its totient is φ = 11294182080000.

The previous prime is 21210121111217. The next prime is 21210121111259. The reversal of 21210121111221 is 12211112101212.

It is a happy number.

21210121111221 is a `hidden beast` number, since 2 + 1 + 210 + 121 + 111 + 221 = 666.

It is not a de Polignac number, because 21210121111221 - 2² = 21210121111217 is a prime.

It is a super-2 number, since 2×21210121111221² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21210121111194 and 21210121111203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210121111321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 97931605 + ... + 98147946.

It is an arithmetic number, because the mean of its divisors is an integer number (780004457856).

Almost surely, 2^{21210121111221} is an apocalyptic number.

21210121111221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21210121111221 is a deficient number, since it is larger than the sum of its proper divisors (16230092865867).

21210121111221 is a wasteful number, since it uses less digits than its factorization.

21210121111221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196079682 (or 196079679 counting only the distinct ones).

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

Adding to 21210121111221 its reverse (12211112101212), we get a palindrome (33421233212433).

The spelling of 21210121111221 in words is "twenty-one trillion, two hundred ten billion, one hundred twenty-one million, one hundred eleven thousand, two hundred twenty-one".