18909865 has 32 divisors (see below), whose sum is σ = 26278560. Its totient is φ = 12939264.

The previous prime is 18909853. The next prime is 18909901. The reversal of 18909865 is 56890981.

It can be written as a sum of positive squares in 16 ways, for example, as 4613904 + 14295961 = 2148^2 + 3781^2 .

It is not a de Polignac number, because 18909865 - 2⁹ = 18909353 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 120367 + ... + 120523.

It is an arithmetic number, because the mean of its divisors is an integer number (821205).

Almost surely, 2^18909865 is an apocalyptic number.

It is an amenable number.

18909865 is a deficient number, since it is larger than the sum of its proper divisors (7368695).

18909865 is a wasteful number, since it uses less digits than its factorization.

18909865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 301.

The product of its (nonzero) digits is 155520, while the sum is 46.

The square root of 18909865 is about 4348.5474586349. The cubic root of 18909865 is about 266.4175372923.

The spelling of 18909865 in words is "eighteen million, nine hundred nine thousand, eight hundred sixty-five".