20018509 has 8 divisors (see below), whose sum is σ = 23345600. Its totient is φ = 17158428.

The previous prime is 20018491. The next prime is 20018527. The reversal of 20018509 is 90581002.

It is an interprime number because it is at equal distance from previous prime (20018491) and next prime (20018527).

It is not a de Polignac number, because 20018509 - 2⁵ = 20018477 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20018909) 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 7 ways as a sum of consecutive naturals, for example, 28839 + ... + 29524.

It is an arithmetic number, because the mean of its divisors is an integer number (2918200).

Almost surely, 2^20018509 is an apocalyptic number.

It is an amenable number.

20018509 is a deficient number, since it is larger than the sum of its proper divisors (3327091).

20018509 is an frugal number, since it uses more digits than its factorization.

20018509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58384 (or 58370 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 20018509 is about 4474.2048455564. The cubic root of 20018509 is about 271.5254711013.

The spelling of 20018509 in words is "twenty million, eighteen thousand, five hundred nine".