18905840 has 20 divisors (see below), whose sum is σ = 43956264. Its totient is φ = 7562304.

The previous prime is 18905813. The next prime is 18905851. The reversal of 18905840 is 4850981.

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

It is a super-2 number, since 2×18905840² = 714861572211200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18905840.

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 3 ways as a sum of consecutive naturals, for example, 118082 + ... + 118241.

Almost surely, 2^18905840 is an apocalyptic number.

18905840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18905840 is an abundant number, since it is smaller than the sum of its proper divisors (25050424).

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

18905840 is a wasteful number, since it uses less digits than its factorization.

18905840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236336 (or 236330 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 35.

The square root of 18905840 is about 4348.0846357908. The cubic root of 18905840 is about 266.3986334613.

The spelling of 18905840 in words is "eighteen million, nine hundred five thousand, eight hundred forty".