18520865 has 24 divisors (see below), whose sum is σ = 25510464. Its totient is φ = 12884080.

The previous prime is 18520841. The next prime is 18520883. The reversal of 18520865 is 56802581.

It is a happy number.

It is not a de Polignac number, because 18520865 - 2¹⁰ = 18519841 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 11.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 805244 + ... + 805266.

It is an arithmetic number, because the mean of its divisors is an integer number (1062936).

Almost surely, 2^18520865 is an apocalyptic number.

It is an amenable number.

18520865 is a deficient number, since it is larger than the sum of its proper divisors (6989599).

18520865 is an frugal number, since it uses more digits than its factorization.

18520865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83 (or 39 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 35.

The square root of 18520865 is about 4303.5874569945. The cubic root of 18520865 is about 264.5780159443.

The spelling of 18520865 in words is "eighteen million, five hundred twenty thousand, eight hundred sixty-five".