21066305 has 8 divisors (see below), whose sum is σ = 27224232. Its totient is φ = 15556608.

The previous prime is 21066299. The next prime is 21066319. The reversal of 21066305 is 50366012.

It can be written as a sum of positive squares in 4 ways, for example, as 1290496 + 19775809 = 1136^2 + 4447^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21066305 - 2⁸ = 21066049 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161984 + ... + 162113.

It is an arithmetic number, because the mean of its divisors is an integer number (3403029).

Almost surely, 2^21066305 is an apocalyptic number.

It is an amenable number.

21066305 is a deficient number, since it is larger than the sum of its proper divisors (6157927).

21066305 is a wasteful number, since it uses less digits than its factorization.

21066305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324115.

The product of its (nonzero) digits is 1080, while the sum is 23.

The square root of 21066305 is about 4589.8044620659. The cubic root of 21066305 is about 276.1824783960.

The spelling of 21066305 in words is "twenty-one million, sixty-six thousand, three hundred five".