18306640 has 80 divisors (see below), whose sum is σ = 47246976. Its totient is φ = 6540800.

The previous prime is 18306599. The next prime is 18306661. The reversal of 18306640 is 4660381.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 18306599 and 18306608.

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, 62334 + ... + 62626.

Almost surely, 2^18306640 is an apocalyptic number.

18306640 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 18306640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23623488).

18306640 is an abundant number, since it is smaller than the sum of its proper divisors (28940336).

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

18306640 is a wasteful number, since it uses less digits than its factorization.

18306640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 388 (or 382 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 18306640 is about 4278.6259476612. The cubic root of 18306640 is about 263.5539606264.

The spelling of 18306640 in words is "eighteen million, three hundred six thousand, six hundred forty".