21201000212221 has 4 divisors (see below), whose sum is σ = 21201035990652. Its totient is φ = 21200964433792.

The previous prime is 21201000212179. The next prime is 21201000212281. The reversal of 21201000212221 is 12221200010212.

It is a happy number.

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 625658852196 + 20575341360025 = 790986^2 + 4536005^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201000212221 - 2¹⁵ = 21201000179453 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201000212195 and 21201000212204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201000212281) 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, 16985140 + ... + 18190573.

It is an arithmetic number, because the mean of its divisors is an integer number (5300258997663).

Almost surely, 2^{21201000212221} is an apocalyptic number.

It is an amenable number.

21201000212221 is a deficient number, since it is larger than the sum of its proper divisors (35778431).

21201000212221 is an equidigital number, since it uses as much as digits as its factorization.

21201000212221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35778430.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21201000212221 its reverse (12221200010212), we get a palindrome (33422200222433).

The spelling of 21201000212221 in words is "twenty-one trillion, two hundred one billion, two hundred twelve thousand, two hundred twenty-one".