20018009 has 4 divisors (see below), whose sum is σ = 21837840. Its totient is φ = 18198180.

The previous prime is 20017997. The next prime is 20018017. The reversal of 20018009 is 90081002.

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 de Polignac number, because none of the positive numbers 2^k-20018009 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20018069) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 909899 + ... + 909920.

It is an arithmetic number, because the mean of its divisors is an integer number (5459460).

Almost surely, 2^20018009 is an apocalyptic number.

It is an amenable number.

20018009 is a deficient number, since it is larger than the sum of its proper divisors (1819831).

20018009 is a wasteful number, since it uses less digits than its factorization.

20018009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1819830.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 20018009 is about 4474.1489693572. The cubic root of 20018009 is about 271.5232104623.

The spelling of 20018009 in words is "twenty million, eighteen thousand, nine".