21406010221 has 2 divisors, whose sum is σ = 21406010222. Its totient is φ = 21406010220.

The previous prime is 21406010191. The next prime is 21406010279. The reversal of 21406010221 is 12201060412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21352515625 + 53494596 = 146125^2 + 7314^2 .

It is a cyclic number.

It is not a de Polignac number, because 21406010221 - 2²⁵ = 21372455789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21406010321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10703005110 + 10703005111.

It is an arithmetic number, because the mean of its divisors is an integer number (10703005111).

Almost surely, 2^21406010221 is an apocalyptic number.

It is an amenable number.

21406010221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21406010221 is an equidigital number, since it uses as much as digits as its factorization.

21406010221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 19.

Adding to 21406010221 its reverse (12201060412), we get a palindrome (33607070633).

The spelling of 21406010221 in words is "twenty-one billion, four hundred six million, ten thousand, two hundred twenty-one".