21215329 has 2 divisors, whose sum is σ = 21215330. Its totient is φ = 21215328.

The previous prime is 21215323. The next prime is 21215339. The reversal of 21215329 is 92351212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20611600 + 603729 = 4540^2 + 777^2 .

It is a cyclic number.

It is not a de Polignac number, because 21215329 - 2³ = 21215321 is a prime.

It is not a weakly prime, because it can be changed into another prime (21215321) 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, 10607664 + 10607665.

It is an arithmetic number, because the mean of its divisors is an integer number (10607665).

Almost surely, 2^21215329 is an apocalyptic number.

It is an amenable number.

21215329 is a deficient number, since it is larger than the sum of its proper divisors (1).

21215329 is an equidigital number, since it uses as much as digits as its factorization.

21215329 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1080, while the sum is 25.

The square root of 21215329 is about 4606.0100955165. The cubic root of 21215329 is about 276.8321912356.

The spelling of 21215329 in words is "twenty-one million, two hundred fifteen thousand, three hundred twenty-nine".