21202221100021 has 4 divisors (see below), whose sum is σ = 22833161184652. Its totient is φ = 19571281015392.

The previous prime is 21202221100009. The next prime is 21202221100033. The reversal of 21202221100021 is 12000112220212.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (21202221100009) and next prime (21202221100033).

It can be written as a sum of positive squares in 2 ways, for example, as 10105494219396 + 11096726880625 = 3178914^2 + 3331175^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202221100021 - 2⁵ = 21202221099989 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21202221099968 and 21202221100004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202221100001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 815470042296 + ... + 815470042321.

It is an arithmetic number, because the mean of its divisors is an integer number (5708290296163).

Almost surely, 2^{21202221100021} is an apocalyptic number.

It is an amenable number.

21202221100021 is a deficient number, since it is larger than the sum of its proper divisors (1630940084631).

21202221100021 is a wasteful number, since it uses less digits than its factorization.

21202221100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1630940084630.

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

Adding to 21202221100021 its reverse (12000112220212), we get a palindrome (33202333320233).

The spelling of 21202221100021 in words is "twenty-one trillion, two hundred two billion, two hundred twenty-one million, one hundred thousand, twenty-one".