18243947 has 4 divisors (see below), whose sum is σ = 18500976. Its totient is φ = 17986920.

The previous prime is 18243917. The next prime is 18243949. The reversal of 18243947 is 74934281.

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 18243947 - 2⁸ = 18243691 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18243947.

It is not an unprimeable number, because it can be changed into a prime (18243949) 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, 128408 + ... + 128549.

It is an arithmetic number, because the mean of its divisors is an integer number (4625244).

Almost surely, 2^18243947 is an apocalyptic number.

18243947 is a deficient number, since it is larger than the sum of its proper divisors (257029).

18243947 is an equidigital number, since it uses as much as digits as its factorization.

18243947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 257028.

The product of its digits is 48384, while the sum is 38.

The square root of 18243947 is about 4271.2933638419. The cubic root of 18243947 is about 263.2527605156.

The spelling of 18243947 in words is "eighteen million, two hundred forty-three thousand, nine hundred forty-seven".