21705227 has 2 divisors, whose sum is σ = 21705228. Its totient is φ = 21705226.

The previous prime is 21705223. The next prime is 21705241. The reversal of 21705227 is 72250712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21705227 - 2² = 21705223 is a prime.

It is a super-2 number, since 2×21705227² = 942233758243058, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21705196 and 21705205.

It is not a weakly prime, because it can be changed into another prime (21705223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10852613 + 10852614.

It is an arithmetic number, because the mean of its divisors is an integer number (10852614).

Almost surely, 2^21705227 is an apocalyptic number.

21705227 is a deficient number, since it is larger than the sum of its proper divisors (1).

21705227 is an equidigital number, since it uses as much as digits as its factorization.

21705227 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1960, while the sum is 26.

The square root of 21705227 is about 4658.8868842246. The cubic root of 21705227 is about 278.9468387897.

Adding to 21705227 its reverse (72250712), we get a palindrome (93955939).

The spelling of 21705227 in words is "twenty-one million, seven hundred five thousand, two hundred twenty-seven".