21100340221 has 2 divisors, whose sum is σ = 21100340222. Its totient is φ = 21100340220.

The previous prime is 21100340213. The next prime is 21100340269. The reversal of 21100340221 is 12204300112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18997108900 + 2103231321 = 137830^2 + 45861^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100340221 - 2³ = 21100340213 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21100340195 and 21100340204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21100340201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550170110 + 10550170111.

It is an arithmetic number, because the mean of its divisors is an integer number (10550170111).

Almost surely, 2^21100340221 is an apocalyptic number.

It is an amenable number.

21100340221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100340221 is an equidigital number, since it uses as much as digits as its factorization.

21100340221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21100340221 its reverse (12204300112), we get a palindrome (33304640333).

The spelling of 21100340221 in words is "twenty-one billion, one hundred million, three hundred forty thousand, two hundred twenty-one".