18420287 has 4 divisors (see below), whose sum is σ = 18812256. Its totient is φ = 18028320.

The previous prime is 18420271. The next prime is 18420289. The reversal of 18420287 is 78202481.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18420287 - 2⁴ = 18420271 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 (18420289) 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, 195914 + ... + 196007.

It is an arithmetic number, because the mean of its divisors is an integer number (4703064).

Almost surely, 2^18420287 is an apocalyptic number.

18420287 is a deficient number, since it is larger than the sum of its proper divisors (391969).

18420287 is an equidigital number, since it uses as much as digits as its factorization.

18420287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 391968.

The product of its (nonzero) digits is 7168, while the sum is 32.

The square root of 18420287 is about 4291.8861820882. The cubic root of 18420287 is about 264.0982139551.

The spelling of 18420287 in words is "eighteen million, four hundred twenty thousand, two hundred eighty-seven".