21332309 has 4 divisors (see below), whose sum is σ = 22020480. Its totient is φ = 20644140.

The previous prime is 21332261. The next prime is 21332329. The reversal of 21332309 is 90323312.

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 not a de Polignac number, because 21332309 - 2⁸ = 21332053 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21332329) 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, 344039 + ... + 344100.

It is an arithmetic number, because the mean of its divisors is an integer number (5505120).

Almost surely, 2^21332309 is an apocalyptic number.

It is an amenable number.

21332309 is a deficient number, since it is larger than the sum of its proper divisors (688171).

21332309 is an equidigital number, since it uses as much as digits as its factorization.

21332309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 688170.

The product of its (nonzero) digits is 972, while the sum is 23.

The square root of 21332309 is about 4618.6912648498. The cubic root of 21332309 is about 277.3400707125.

The spelling of 21332309 in words is "twenty-one million, three hundred thirty-two thousand, three hundred nine".