18021890509 has 8 divisors (see below), whose sum is σ = 20604841920. Its totient is φ = 15441038016.

The previous prime is 18021890449. The next prime is 18021890527. The reversal of 18021890509 is 90509812081.

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

It is a cyclic number.

It is not a de Polignac number, because 18021890509 - 2¹¹ = 18021888461 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 (18021890539) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 506284 + ... + 540709.

It is an arithmetic number, because the mean of its divisors is an integer number (2575605240).

Almost surely, 2^18021890509 is an apocalyptic number.

It is an amenable number.

18021890509 is a deficient number, since it is larger than the sum of its proper divisors (2582951411).

18021890509 is a wasteful number, since it uses less digits than its factorization.

18021890509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1049459.

The product of its (nonzero) digits is 51840, while the sum is 43.

The spelling of 18021890509 in words is "eighteen billion, twenty-one million, eight hundred ninety thousand, five hundred nine".