18439985 has 16 divisors (see below), whose sum is σ = 23531472. Its totient is φ = 13824000.

The previous prime is 18439979. The next prime is 18440011. The reversal of 18439985 is 58993481.

It can be written as a sum of positive squares in 8 ways, for example, as 2383936 + 16056049 = 1544^2 + 4007^2 .

It is not a de Polignac number, because 18439985 - 2⁶ = 18439921 is a prime.

It is a Duffinian 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, 33815 + ... + 34355.

It is an arithmetic number, because the mean of its divisors is an integer number (1470717).

Almost surely, 2^18439985 is an apocalyptic number.

It is an amenable number.

18439985 is a deficient number, since it is larger than the sum of its proper divisors (5091487).

18439985 is a wasteful number, since it uses less digits than its factorization.

18439985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 964.

The product of its digits is 311040, while the sum is 47.

The square root of 18439985 is about 4294.1803641673. The cubic root of 18439985 is about 264.1923194987.

The spelling of 18439985 in words is "eighteen million, four hundred thirty-nine thousand, nine hundred eighty-five".