18641987 has 8 divisors (see below), whose sum is σ = 22944096. Its totient is φ = 14749632.

The previous prime is 18641981. The next prime is 18641989. The reversal of 18641987 is 78914681.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18641987 - 2⁶ = 18641923 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18641981) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 102338 + ... + 102519.

It is an arithmetic number, because the mean of its divisors is an integer number (2868012).

Almost surely, 2^18641987 is an apocalyptic number.

18641987 is a deficient number, since it is larger than the sum of its proper divisors (4302109).

18641987 is a wasteful number, since it uses less digits than its factorization.

18641987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204877.

The product of its digits is 96768, while the sum is 44.

The square root of 18641987 is about 4317.6367378463. The cubic root of 18641987 is about 265.1535220553.

The spelling of 18641987 in words is "eighteen million, six hundred forty-one thousand, nine hundred eighty-seven".