21324420121221 has 80 divisors (see below), whose sum is σ = 37475015364864. Its totient is φ = 11832216155136.

The previous prime is 21324420121211. The next prime is 21324420121259. The reversal of 21324420121221 is 12212102442312.

21324420121221 is a `hidden beast` number, since 2 + 1 + 3 + 2 + 4 + 420 + 1 + 212 + 21 = 666.

It is not a de Polignac number, because 21324420121221 - 2⁵ = 21324420121189 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21324420121211) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 742825 + ... + 6572718.

Almost surely, 2^{21324420121221} is an apocalyptic number.

21324420121221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21324420121221 is a deficient number, since it is larger than the sum of its proper divisors (16150595243643).

21324420121221 is an equidigital number, since it uses as much as digits as its factorization.

21324420121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7315712 (or 7315703 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

Adding to 21324420121221 its reverse (12212102442312), we get a palindrome (33536522563533).

The spelling of 21324420121221 in words is "twenty-one trillion, three hundred twenty-four billion, four hundred twenty million, one hundred twenty-one thousand, two hundred twenty-one".