21433309 has 4 divisors (see below), whose sum is σ = 22365216. Its totient is φ = 20501404.

The previous prime is 21433289. The next prime is 21433319. The reversal of 21433309 is 90333412.

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 21433309 - 2²³ = 13044701 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 (21433319) 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, 465919 + ... + 465964.

It is an arithmetic number, because the mean of its divisors is an integer number (5591304).

Almost surely, 2^21433309 is an apocalyptic number.

It is an amenable number.

21433309 is a deficient number, since it is larger than the sum of its proper divisors (931907).

21433309 is an equidigital number, since it uses as much as digits as its factorization.

21433309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 931906.

The product of its (nonzero) digits is 1944, while the sum is 25.

The square root of 21433309 is about 4629.6121867820. The cubic root of 21433309 is about 277.7770800634. Note that the first 3 decimals are identical.

The spelling of 21433309 in words is "twenty-one million, four hundred thirty-three thousand, three hundred nine".