21066369 has 4 divisors (see below), whose sum is σ = 28088496. Its totient is φ = 14044244.

The previous prime is 21066361. The next prime is 21066371. The reversal of 21066369 is 96366012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21066369 - 2³ = 21066361 is a prime.

It is a super-2 number, since 2×21066369² = 887583805688322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21066361) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3511059 + ... + 3511064.

It is an arithmetic number, because the mean of its divisors is an integer number (7022124).

Almost surely, 2^21066369 is an apocalyptic number.

It is an amenable number.

21066369 is a deficient number, since it is larger than the sum of its proper divisors (7022127).

21066369 is an equidigital number, since it uses as much as digits as its factorization.

21066369 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7022126.

The product of its (nonzero) digits is 11664, while the sum is 33.

The square root of 21066369 is about 4589.8114340352. The cubic root of 21066369 is about 276.1827580790.

The spelling of 21066369 in words is "twenty-one million, sixty-six thousand, three hundred sixty-nine".