18242509 has 4 divisors (see below), whose sum is σ = 18375804. Its totient is φ = 18109216.

The previous prime is 18242507. The next prime is 18242551. The reversal of 18242509 is 90524281.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90524281 = 821 ⋅110261.

It can be written as a sum of positive squares in 2 ways, for example, as 4202500 + 14040009 = 2050^2 + 3747^2 .

It is a cyclic number.

It is not a de Polignac number, because 18242509 - 2¹ = 18242507 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18242503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66442 + ... + 66715.

It is an arithmetic number, because the mean of its divisors is an integer number (4593951).

Almost surely, 2^18242509 is an apocalyptic number.

It is an amenable number.

18242509 is a deficient number, since it is larger than the sum of its proper divisors (133295).

18242509 is a wasteful number, since it uses less digits than its factorization.

18242509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133294.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 18242509 is about 4271.1250274372. The cubic root of 18242509 is about 263.2458437482.

The spelling of 18242509 in words is "eighteen million, two hundred forty-two thousand, five hundred nine".