21030009 has 64 divisors (see below), whose sum is σ = 38707200. Its totient is φ = 9803520.

The previous prime is 21030001. The next prime is 21030043. The reversal of 21030009 is 90003012.

It is not a de Polignac number, because 21030009 - 2³ = 21030001 is a prime.

It is a super-2 number, since 2×21030009² = 884522557080162, 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 21030009.

It is not an unprimeable number, because it can be changed into a prime (21030001) 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 63 ways as a sum of consecutive naturals, for example, 141067 + ... + 141215.

It is an arithmetic number, because the mean of its divisors is an integer number (604800).

Almost surely, 2^21030009 is an apocalyptic number.

It is an amenable number.

21030009 is a deficient number, since it is larger than the sum of its proper divisors (17677191).

21030009 is a wasteful number, since it uses less digits than its factorization.

21030009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 230.

The product of its (nonzero) digits is 54, while the sum is 15.

The square root of 21030009 is about 4585.8487763990. The cubic root of 21030009 is about 276.0237718445.

The spelling of 21030009 in words is "twenty-one million, thirty thousand, nine".