18399563 has 32 divisors (see below), whose sum is σ = 24192000. Its totient is φ = 13597056.

The previous prime is 18399551. The next prime is 18399587. The reversal of 18399563 is 36599381.

It is a cyclic number.

It is not a de Polignac number, because 18399563 - 2⁶ = 18399499 is a prime.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (18390563) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 123413 + ... + 123561.

It is an arithmetic number, because the mean of its divisors is an integer number (756000).

Almost surely, 2^18399563 is an apocalyptic number.

18399563 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

18399563 is a deficient number, since it is larger than the sum of its proper divisors (5792437).

18399563 is a wasteful number, since it uses less digits than its factorization.

18399563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251.

The product of its digits is 174960, while the sum is 44.

The square root of 18399563 is about 4289.4711795278. The cubic root of 18399563 is about 263.9991343329. Note that the first 3 decimals are identical.

The spelling of 18399563 in words is "eighteen million, three hundred ninety-nine thousand, five hundred sixty-three".