21330309 has 32 divisors (see below), whose sum is σ = 38191104. Its totient is φ = 10226880.

The previous prime is 21330299. The next prime is 21330311. The reversal of 21330309 is 90303312.

It is not a de Polignac number, because 21330309 - 2¹² = 21326213 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21331309) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 549 + ... + 6554.

It is an arithmetic number, because the mean of its divisors is an integer number (1193472).

Almost surely, 2^21330309 is an apocalyptic number.

It is an amenable number.

21330309 is a deficient number, since it is larger than the sum of its proper divisors (16860795).

21330309 is a wasteful number, since it uses less digits than its factorization.

21330309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7137.

The product of its (nonzero) digits is 486, while the sum is 21.

The square root of 21330309 is about 4618.4747482259. The cubic root of 21330309 is about 277.3314031483.

The spelling of 21330309 in words is "twenty-one million, three hundred thirty thousand, three hundred nine".