18431985 has 48 divisors (see below), whose sum is σ = 34890048. Its totient is φ = 8236800.

The previous prime is 18431983. The next prime is 18431999. The reversal of 18431985 is 58913481.

It is not a de Polignac number, because 18431985 - 2¹ = 18431983 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18431983) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 27555 + ... + 28215.

It is an arithmetic number, because the mean of its divisors is an integer number (726876).

Almost surely, 2^18431985 is an apocalyptic number.

18431985 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18431985 is a deficient number, since it is larger than the sum of its proper divisors (16458063).

18431985 is a wasteful number, since it uses less digits than its factorization.

18431985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 706 (or 693 counting only the distinct ones).

The product of its digits is 34560, while the sum is 39.

The square root of 18431985 is about 4293.2487698711. The cubic root of 18431985 is about 264.1541082551.

It can be divided in two parts, 1843 and 1985, that added together give a triangular number (3828 = T₈₇).

The spelling of 18431985 in words is "eighteen million, four hundred thirty-one thousand, nine hundred eighty-five".