18520643 has 4 divisors (see below), whose sum is σ = 18972408. Its totient is φ = 18068880.

The previous prime is 18520613. The next prime is 18520693. The reversal of 18520643 is 34602581.

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 18520643 - 2²² = 14326339 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18520613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 225821 + ... + 225902.

It is an arithmetic number, because the mean of its divisors is an integer number (4743102).

Almost surely, 2^18520643 is an apocalyptic number.

18520643 is a deficient number, since it is larger than the sum of its proper divisors (451765).

18520643 is an equidigital number, since it uses as much as digits as its factorization.

18520643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 451764.

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 18520643 is about 4303.5616644821. The cubic root of 18520643 is about 264.5769588203.

The spelling of 18520643 in words is "eighteen million, five hundred twenty thousand, six hundred forty-three".