21221202100221 has 6 divisors (see below), whose sum is σ = 30652847478110. Its totient is φ = 14147468066808.

The previous prime is 21221202100201. The next prime is 21221202100223. The reversal of 21221202100221 is 12200120212212.

It is a happy number.

21221202100221 is a `hidden beast` number, since 21 + 2 + 212 + 0 + 210 + 0 + 221 = 666.

It can be written as a sum of positive squares in only one way, i.e., 13805765103321 + 7415436996900 = 3715611^2 + 2723130^2 .

It is not a de Polignac number, because 21221202100221 - 2¹⁵ = 21221202067453 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221202100194 and 21221202100203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221202100223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1178955672226 + ... + 1178955672243.

Almost surely, 2^{21221202100221} is an apocalyptic number.

It is an amenable number.

21221202100221 is a deficient number, since it is larger than the sum of its proper divisors (9431645377889).

21221202100221 is a wasteful number, since it uses less digits than its factorization.

21221202100221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2357911344475 (or 2357911344472 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21221202100221 its reverse (12200120212212), we get a palindrome (33421322312433).

The spelling of 21221202100221 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred two million, one hundred thousand, two hundred twenty-one".