381840 has 80 divisors (see below), whose sum is σ = 1243968. Its totient is φ = 96768.

The previous prime is 381817. The next prime is 381841. The reversal of 381840 is 48183.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 381840.

It is not an unprimeable number, because it can be changed into a prime (381841) 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, 8859 + ... + 8901.

2³⁸¹⁸⁴⁰ is an apocalyptic number.

381840 is a gapful number since it is divisible by the number (30) 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 381840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (621984).

381840 is an abundant number, since it is smaller than the sum of its proper divisors (862128).

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

381840 is a wasteful number, since it uses less digits than its factorization.

381840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96 (or 90 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 381840 is about 617.9320350977. The cubic root of 381840 is about 72.5482833347.

It can be divided in two parts, 381 and 840, that added together give a palindrome (1221).

The spelling of 381840 in words is "three hundred eighty-one thousand, eight hundred forty".