123840 has 84 divisors (see below), whose sum is σ = 435864. Its totient is φ = 32256.

The previous prime is 123833. The next prime is 123853. The reversal of 123840 is 48321.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

123840 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 11 ways as a sum of consecutive naturals, for example, 2859 + ... + 2901.

123840 is a Friedman number, since it can be written as 4128*30, using all its digits and the basic arithmetic operations.

2¹²³⁸⁴⁰ is an apocalyptic number.

123840 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 123840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (217932).

123840 is an abundant number, since it is smaller than the sum of its proper divisors (312024).

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

123840 is a wasteful number, since it uses less digits than its factorization.

123840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 123840 is about 351.9090791668. The cubic root of 123840 is about 49.8448524158.

The spelling of 123840 in words is "one hundred twenty-three thousand, eight hundred forty".