423840 has 48 divisors (see below), whose sum is σ = 1336608. Its totient is φ = 112896.

The previous prime is 423823. The next prime is 423847. The reversal of 423840 is 48324.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is not an unprimeable number, because it can be changed into a prime (423847) by changing a digit.

423840 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39 + ... + 921.

It is an arithmetic number, because the mean of its divisors is an integer number (27846).

2⁴²³⁸⁴⁰ is an apocalyptic number.

423840 is a gapful number since it is divisible by the number (40) 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 423840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (668304).

423840 is an abundant number, since it is smaller than the sum of its proper divisors (912768).

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

423840 is a wasteful number, since it uses less digits than its factorization.

423840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 901 (or 893 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 21.

The square root of 423840 is about 651.0299532280. The cubic root of 423840 is about 75.1162641200.

It can be divided in two parts, 4238 and 40, that added together give a triangular number (4278 = T₉₂).

The spelling of 423840 in words is "four hundred twenty-three thousand, eight hundred forty".