18418640 has 20 divisors (see below), whose sum is σ = 42823524. Its totient is φ = 7367424.

The previous prime is 18418627. The next prime is 18418643. The reversal of 18418640 is 4681481.

It can be written as a sum of positive squares in 2 ways, for example, as 13017664 + 5400976 = 3608^2 + 2324^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 18418597 and 18418606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18418643) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 115037 + ... + 115196.

Almost surely, 2^18418640 is an apocalyptic number.

18418640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18418640 is an abundant number, since it is smaller than the sum of its proper divisors (24404884).

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

18418640 is a wasteful number, since it uses less digits than its factorization.

18418640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230246 (or 230240 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 32.

The square root of 18418640 is about 4291.6943041181. The cubic root of 18418640 is about 264.0903425120.

The spelling of 18418640 in words is "eighteen million, four hundred eighteen thousand, six hundred forty".