18665640 has 160 divisors (see below), whose sum is σ = 71786880. Its totient is φ = 4261248.

The previous prime is 18665639. The next prime is 18665651. The reversal of 18665640 is 4656681.

18665640 is a `hidden beast` number, since 1 + 8 + 6 + 6 + 5 + 640 = 666.

It is a super-2 number, since 2×18665640² = 696812233219200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 18665595 and 18665604.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 22269 + ... + 23091.

It is an arithmetic number, because the mean of its divisors is an integer number (448668).

Almost surely, 2^18665640 is an apocalyptic number.

18665640 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 18665640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35893440).

18665640 is an abundant number, since it is smaller than the sum of its proper divisors (53121240).

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

18665640 is a wasteful number, since it uses less digits than its factorization.

18665640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 853 (or 840 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 18665640 is about 4320.3749837254. The cubic root of 18665640 is about 265.2656171451.

The spelling of 18665640 in words is "eighteen million, six hundred sixty-five thousand, six hundred forty".