18631985 has 4 divisors (see below), whose sum is σ = 22358388. Its totient is φ = 14905584.

The previous prime is 18631957. The next prime is 18631993. The reversal of 18631985 is 58913681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 58913681 = 2543 ⋅23167.

It can be written as a sum of positive squares in 2 ways, for example, as 12794929 + 5837056 = 3577^2 + 2416^2 .

It is a cyclic number.

It is not a de Polignac number, because 18631985 - 2²⁰ = 17583409 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 (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1863194 + ... + 1863203.

It is an arithmetic number, because the mean of its divisors is an integer number (5589597).

Almost surely, 2^18631985 is an apocalyptic number.

It is an amenable number.

18631985 is a deficient number, since it is larger than the sum of its proper divisors (3726403).

18631985 is an equidigital number, since it uses as much as digits as its factorization.

18631985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3726402.

The product of its digits is 51840, while the sum is 41.

The square root of 18631985 is about 4316.4783099189. The cubic root of 18631985 is about 265.1060925624.

The spelling of 18631985 in words is "eighteen million, six hundred thirty-one thousand, nine hundred eighty-five".