21435009 has 4 divisors (see below), whose sum is σ = 28580016. Its totient is φ = 14290004.

The previous prime is 21434957. The next prime is 21435017. The reversal of 21435009 is 90053412.

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 21435009 - 2⁸ = 21434753 is a prime.

It is a super-2 number, since 2×21435009² = 918919221660162, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21435009.

It is not an unprimeable number, because it can be changed into a prime (21435019) 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, 3572499 + ... + 3572504.

It is an arithmetic number, because the mean of its divisors is an integer number (7145004).

Almost surely, 2^21435009 is an apocalyptic number.

It is an amenable number.

21435009 is a deficient number, since it is larger than the sum of its proper divisors (7145007).

21435009 is an equidigital number, since it uses as much as digits as its factorization.

21435009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7145006.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21435009 is about 4629.7957838332. The cubic root of 21435009 is about 277.7844239062.

The spelling of 21435009 in words is "twenty-one million, four hundred thirty-five thousand, nine".