18720645 has 16 divisors (see below), whose sum is σ = 30056832. Its totient is φ = 9949760.

The previous prime is 18720619. The next prime is 18720661. The reversal of 18720645 is 54602781.

It is not a de Polignac number, because 18720645 - 2⁸ = 18720389 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2659 + ... + 6671.

It is an arithmetic number, because the mean of its divisors is an integer number (1878552).

Almost surely, 2^18720645 is an apocalyptic number.

18720645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18720645 is a deficient number, since it is larger than the sum of its proper divisors (11336187).

18720645 is a wasteful number, since it uses less digits than its factorization.

18720645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4332.

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 18720645 is about 4326.7360677536. The cubic root of 18720645 is about 265.5259283589.

The spelling of 18720645 in words is "eighteen million, seven hundred twenty thousand, six hundred forty-five".