18687640 has 64 divisors (see below), whose sum is σ = 45043200. Its totient is φ = 6956928.

The previous prime is 18687587. The next prime is 18687731. The reversal of 18687640 is 4678681.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 18687593 and 18687602.

It is a congruent 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 15 ways as a sum of consecutive naturals, for example, 50737 + ... + 51103.

It is an arithmetic number, because the mean of its divisors is an integer number (703800).

Almost surely, 2^18687640 is an apocalyptic number.

18687640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18687640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22521600).

18687640 is an abundant number, since it is smaller than the sum of its proper divisors (26355560).

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

18687640 is a wasteful number, since it uses less digits than its factorization.

18687640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 464 (or 460 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 40.

The square root of 18687640 is about 4322.9203092354. The cubic root of 18687640 is about 265.3697934516.

The spelling of 18687640 in words is "eighteen million, six hundred eighty-seven thousand, six hundred forty".