393840 has 60 divisors (see below), whose sum is σ = 1325064. Its totient is φ = 104832.

The previous prime is 393797. The next prime is 393847. The reversal of 393840 is 48393.

It is a tau number, because it is divible by the number of its divisors (60).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (393847) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 447 + ... + 993.

2³⁹³⁸⁴⁰ is an apocalyptic number.

393840 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 393840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (662532).

393840 is an abundant number, since it is smaller than the sum of its proper divisors (931224).

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

393840 is a wasteful number, since it uses less digits than its factorization.

393840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 566 (or 557 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 393840 is about 627.5667295197. The cubic root of 393840 is about 73.3004443888.

The spelling of 393840 in words is "three hundred ninety-three thousand, eight hundred forty".