21430509 has 8 divisors (see below), whose sum is σ = 28718400. Its totient is φ = 14214816.

The previous prime is 21430481. The next prime is 21430529. The reversal of 21430509 is 90503412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21430509 - 2⁵ = 21430477 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21430529) 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 7 ways as a sum of consecutive naturals, for example, 17352 + ... + 18545.

It is an arithmetic number, because the mean of its divisors is an integer number (3589800).

Almost surely, 2^21430509 is an apocalyptic number.

It is an amenable number.

21430509 is a deficient number, since it is larger than the sum of its proper divisors (7287891).

21430509 is a wasteful number, since it uses less digits than its factorization.

21430509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36099.

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

The square root of 21430509 is about 4629.3097757657. The cubic root of 21430509 is about 277.7649834759.

The spelling of 21430509 in words is "twenty-one million, four hundred thirty thousand, five hundred nine".