18687444 has 12 divisors (see below), whose sum is σ = 43604064. Its totient is φ = 6229144.

The previous prime is 18687433. The next prime is 18687457. The reversal of 18687444 is 44478681.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 18687396 and 18687405.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 778632 + ... + 778655.

It is an arithmetic number, because the mean of its divisors is an integer number (3633672).

Almost surely, 2^18687444 is an apocalyptic number.

It is an amenable number.

18687444 is an abundant number, since it is smaller than the sum of its proper divisors (24916620).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18687444 is a wasteful number, since it uses less digits than its factorization.

18687444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1557294 (or 1557292 counting only the distinct ones).

The product of its digits is 172032, while the sum is 42.

The square root of 18687444 is about 4322.8976393156. The cubic root of 18687444 is about 265.3688656964.

The spelling of 18687444 in words is "eighteen million, six hundred eighty-seven thousand, four hundred forty-four".