21000201122221 has 4 divisors (see below), whose sum is σ = 21141142069500. Its totient is φ = 20859260174944.

The previous prime is 21000201122203. The next prime is 21000201122357. The reversal of 21000201122221 is 12222110200012.

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 2863794675625 + 18136406446596 = 1692275^2 + 4258686^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000201122221 - 2¹⁷ = 21000200991149 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21000201122195 and 21000201122204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000201123221) 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, 70470473416 + ... + 70470473713.

It is an arithmetic number, because the mean of its divisors is an integer number (5285285517375).

Almost surely, 2^{21000201122221} is an apocalyptic number.

It is an amenable number.

21000201122221 is a deficient number, since it is larger than the sum of its proper divisors (140940947279).

21000201122221 is a wasteful number, since it uses less digits than its factorization.

21000201122221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140940947278.

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

Adding to 21000201122221 its reverse (12222110200012), we get a palindrome (33222311322233).

The spelling of 21000201122221 in words is "twenty-one trillion, two hundred one million, one hundred twenty-two thousand, two hundred twenty-one".