281840 has 40 divisors (see below), whose sum is σ = 708288. Its totient is φ = 103680.

The previous prime is 281839. The next prime is 281849. The reversal of 281840 is 48182.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (281849) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 905 + ... + 1175.

2²⁸¹⁸⁴⁰ is an apocalyptic number.

281840 is a gapful number since it is divisible by the number (20) 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 281840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (354144).

281840 is an abundant number, since it is smaller than the sum of its proper divisors (426448).

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

281840 is a wasteful number, since it uses less digits than its factorization.

281840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 297 (or 291 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 23.

The square root of 281840 is about 530.8860518040. The cubic root of 281840 is about 65.5643172985.

The spelling of 281840 in words is "two hundred eighty-one thousand, eight hundred forty".