18939840 has 112 divisors (see below), whose sum is σ = 61020960. Its totient is φ = 4976640.

The previous prime is 18939803. The next prime is 18939841. The reversal of 18939840 is 4893981.

It is a junction number, because it is equal to n+sod(n) for n = 18939792 and 18939801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18939841) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 104550 + ... + 104730.

It is an arithmetic number, because the mean of its divisors is an integer number (544830).

Almost surely, 2^18939840 is an apocalyptic number.

18939840 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 18939840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30510480).

18939840 is an abundant number, since it is smaller than the sum of its proper divisors (42081120).

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

18939840 is a wasteful number, since it uses less digits than its factorization.

18939840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 310 (or 300 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 42.

The square root of 18939840 is about 4351.9926470526. The cubic root of 18939840 is about 266.5582336923.

The spelling of 18939840 in words is "eighteen million, nine hundred thirty-nine thousand, eight hundred forty".