18642643 has 4 divisors (see below), whose sum is σ = 18958680. Its totient is φ = 18326608.

The previous prime is 18642641. The next prime is 18642647. The reversal of 18642643 is 34624681.

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 18642643 - 2¹ = 18642641 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18642599 and 18642608.

It is not an unprimeable number, because it can be changed into a prime (18642641) 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, 157930 + ... + 158047.

It is an arithmetic number, because the mean of its divisors is an integer number (4739670).

Almost surely, 2^18642643 is an apocalyptic number.

18642643 is a deficient number, since it is larger than the sum of its proper divisors (316037).

18642643 is an equidigital number, since it uses as much as digits as its factorization.

18642643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316036.

The product of its digits is 27648, while the sum is 34.

The square root of 18642643 is about 4317.7127046620. The cubic root of 18642643 is about 265.1566322150.

The spelling of 18642643 in words is "eighteen million, six hundred forty-two thousand, six hundred forty-three".