18856809 has 6 divisors (see below), whose sum is σ = 27237626. Its totient is φ = 12571200.

The previous prime is 18856777. The next prime is 18856829. The reversal of 18856809 is 90865881.

18856809 is a `hidden beast` number, since 1 + 88 + 568 + 0 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 15776784 + 3080025 = 3972^2 + 1755^2 .

It is not a de Polignac number, because 18856809 - 2⁵ = 18856777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18856829) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1047592 + ... + 1047609.

Almost surely, 2^18856809 is an apocalyptic number.

It is an amenable number.

18856809 is a deficient number, since it is larger than the sum of its proper divisors (8380817).

18856809 is a wasteful number, since it uses less digits than its factorization.

18856809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2095207 (or 2095204 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 45.

The square root of 18856809 is about 4342.4427457366. The cubic root of 18856809 is about 266.1681385575.

The spelling of 18856809 in words is "eighteen million, eight hundred fifty-six thousand, eight hundred nine".