18181908 has 60 divisors (see below), whose sum is σ = 50342292. Its totient is φ = 5702400.

The previous prime is 18181907. The next prime is 18181909. The reversal of 18181908 is 80918181.

It is an interprime number because it is at equal distance from previous prime (18181907) and next prime (18181909).

It can be written as a sum of positive squares in 2 ways, for example, as 8928144 + 9253764 = 2988^2 + 3042^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18181907) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3858 + ... + 7158.

Almost surely, 2^18181908 is an apocalyptic number.

18181908 is a gapful number since it is divisible by the number (18) 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 18181908, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25171146).

18181908 is an abundant number, since it is smaller than the sum of its proper divisors (32160384).

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

18181908 is a wasteful number, since it uses less digits than its factorization.

18181908 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3334 (or 3323 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 36.

The square root of 18181908 is about 4264.0248592146. The cubic root of 18181908 is about 262.9540224291.

The spelling of 18181908 in words is "eighteen million, one hundred eighty-one thousand, nine hundred eight".