18501640 has 16 divisors (see below), whose sum is σ = 41628780. Its totient is φ = 7400640.

The previous prime is 18501629. The next prime is 18501647. The reversal of 18501640 is 4610581.

It can be written as a sum of positive squares in 2 ways, for example, as 17322244 + 1179396 = 4162^2 + 1086^2 .

It is not an unprimeable number, because it can be changed into a prime (18501647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 231231 + ... + 231310.

Almost surely, 2^18501640 is an apocalyptic number.

18501640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18501640 is an abundant number, since it is smaller than the sum of its proper divisors (23127140).

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

18501640 is a wasteful number, since it uses less digits than its factorization.

18501640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 462552 (or 462548 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 18501640 is about 4301.3532754239. The cubic root of 18501640 is about 264.4864386280.

The spelling of 18501640 in words is "eighteen million, five hundred one thousand, six hundred forty".