21120221202221 has 4 divisors (see below), whose sum is σ = 21121046591100. Its totient is φ = 21119395813344.

The previous prime is 21120221202211. The next prime is 21120221202233. The reversal of 21120221202221 is 12220212202112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11809704075625 + 9310517126596 = 3436525^2 + 3051314^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120221202221 - 2¹⁴ = 21120221185837 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21120221202193 and 21120221202202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120221202211) 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 3 ways as a sum of consecutive naturals, for example, 412656056 + ... + 412707233.

It is an arithmetic number, because the mean of its divisors is an integer number (5280261647775).

Almost surely, 2^{21120221202221} is an apocalyptic number.

It is an amenable number.

21120221202221 is a deficient number, since it is larger than the sum of its proper divisors (825388879).

21120221202221 is an equidigital number, since it uses as much as digits as its factorization.

21120221202221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 825388878.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21120221202221 its reverse (12220212202112), we get a palindrome (33340433404333).

The spelling of 21120221202221 in words is "twenty-one trillion, one hundred twenty billion, two hundred twenty-one million, two hundred two thousand, two hundred twenty-one".