21532009 has 4 divisors (see below), whose sum is σ = 21548800. Its totient is φ = 21515220.

The previous prime is 21531989. The next prime is 21532019. The reversal of 21532009 is 90023512.

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 21532009 - 2⁵ = 21531977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21532019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6297 + ... + 9094.

It is an arithmetic number, because the mean of its divisors is an integer number (5387200).

Almost surely, 2^21532009 is an apocalyptic number.

It is an amenable number.

21532009 is a deficient number, since it is larger than the sum of its proper divisors (16791).

21532009 is a wasteful number, since it uses less digits than its factorization.

21532009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16790.

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 21532009 is about 4640.2595832561. The cubic root of 21532009 is about 278.2028133745.

The spelling of 21532009 in words is "twenty-one million, five hundred thirty-two thousand, nine".