18007643 has 4 divisors (see below), whose sum is σ = 18790608. Its totient is φ = 17224680.

The previous prime is 18007609. The next prime is 18007663. The reversal of 18007643 is 34670081.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 34670081 = 71 ⋅488311.

It is a cyclic number.

It is not a de Polignac number, because 18007643 - 2¹⁸ = 17745499 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18007663) 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, 391448 + ... + 391493.

It is an arithmetic number, because the mean of its divisors is an integer number (4697652).

Almost surely, 2^18007643 is an apocalyptic number.

18007643 is a deficient number, since it is larger than the sum of its proper divisors (782965).

18007643 is an equidigital number, since it uses as much as digits as its factorization.

18007643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 782964.

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 18007643 is about 4243.5413277120. The cubic root of 18007643 is about 262.1112273692. Note that the first 3 decimals are identical.

The spelling of 18007643 in words is "eighteen million, seven thousand, six hundred forty-three".