21165229 has 2 divisors, whose sum is σ = 21165230. Its totient is φ = 21165228.

The previous prime is 21165227. The next prime is 21165241. The reversal of 21165229 is 92256112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12888100 + 8277129 = 3590^2 + 2877^2 .

It is a cyclic number.

It is not a de Polignac number, because 21165229 - 2¹ = 21165227 is a prime.

Together with 21165227, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21165197 and 21165206.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21165227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10582614 + 10582615.

It is an arithmetic number, because the mean of its divisors is an integer number (10582615).

Almost surely, 2^21165229 is an apocalyptic number.

It is an amenable number.

21165229 is a deficient number, since it is larger than the sum of its proper divisors (1).

21165229 is an equidigital number, since it uses as much as digits as its factorization.

21165229 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2160, while the sum is 28.

The square root of 21165229 is about 4600.5683344561. The cubic root of 21165229 is about 276.6141064006.

The spelling of 21165229 in words is "twenty-one million, one hundred sixty-five thousand, two hundred twenty-nine".