18871990 has 8 divisors (see below), whose sum is σ = 33969600. Its totient is φ = 7548792.

The previous prime is 18871981. The next prime is 18871999. The reversal of 18871990 is 9917881.

It is an interprime number because it is at equal distance from previous prime (18871981) and next prime (18871999).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18871999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 943590 + ... + 943609.

It is an arithmetic number, because the mean of its divisors is an integer number (4246200).

Almost surely, 2^18871990 is an apocalyptic number.

18871990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18871990 is a deficient number, since it is larger than the sum of its proper divisors (15097610).

18871990 is a wasteful number, since it uses less digits than its factorization.

18871990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1887206.

The product of its (nonzero) digits is 36288, while the sum is 43.

The square root of 18871990 is about 4344.1903733607. The cubic root of 18871990 is about 266.2395471515.

The spelling of 18871990 in words is "eighteen million, eight hundred seventy-one thousand, nine hundred ninety".