21120001221 has 48 divisors (see below), whose sum is σ = 33429912768. Its totient is φ = 11753011200.

The previous prime is 21120001219. The next prime is 21120001261. The reversal of 21120001221 is 12210002112.

It is not a de Polignac number, because 21120001221 - 2¹ = 21120001219 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21120001197 and 21120001206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120001261) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 364011 + ... + 418023.

It is an arithmetic number, because the mean of its divisors is an integer number (696456516).

Almost surely, 2^21120001221 is an apocalyptic number.

It is an amenable number.

21120001221 is a deficient number, since it is larger than the sum of its proper divisors (12309911547).

21120001221 is a wasteful number, since it uses less digits than its factorization.

21120001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54102 (or 54085 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21120001221 its reverse (12210002112), we get a palindrome (33330003333).

The spelling of 21120001221 in words is "twenty-one billion, one hundred twenty million, one thousand, two hundred twenty-one".