21211210202221 has 8 divisors (see below), whose sum is σ = 22925306892824. Its totient is φ = 19508894245440.

The previous prime is 21211210202201. The next prime is 21211210202261. The reversal of 21211210202221 is 12220201211212.

It can be written as a sum of positive squares in 4 ways, for example, as 227160904996 + 20984049297225 = 476614^2 + 4580835^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21211210202221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211210202201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2945179710 + ... + 2945186911.

It is an arithmetic number, because the mean of its divisors is an integer number (2865663361603).

Almost surely, 2^{21211210202221} is an apocalyptic number.

It is an amenable number.

21211210202221 is a deficient number, since it is larger than the sum of its proper divisors (1714096690603).

21211210202221 is a wasteful number, since it uses less digits than its factorization.

21211210202221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5890366911.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21211210202221 its reverse (12220201211212), we get a palindrome (33431411413433).

The spelling of 21211210202221 in words is "twenty-one trillion, two hundred eleven billion, two hundred ten million, two hundred two thousand, two hundred twenty-one".