18013509 has 10 divisors (see below), whose sum is σ = 26909190. Its totient is φ = 12008952.

The previous prime is 18013507. The next prime is 18013529. The reversal of 18013509 is 90531081.

It can be written as a sum of positive squares in only one way, i.e., 13616100 + 4397409 = 3690^2 + 2097^2 .

It is not a de Polignac number, because 18013509 - 2¹ = 18013507 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18013507) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 111114 + ... + 111275.

It is an arithmetic number, because the mean of its divisors is an integer number (2690919).

Almost surely, 2^18013509 is an apocalyptic number.

It is an amenable number.

18013509 is a deficient number, since it is larger than the sum of its proper divisors (8895681).

18013509 is an equidigital number, since it uses as much as digits as its factorization.

18013509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222401 (or 222392 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 27.

The square root of 18013509 is about 4244.2324394406. The cubic root of 18013509 is about 262.1396852401.

It can be divided in two parts, 180 and 13509, that added together give a square (13689 = 117²).

The spelling of 18013509 in words is "eighteen million, thirteen thousand, five hundred nine".