135840 has 48 divisors (see below), whose sum is σ = 429408. Its totient is φ = 36096.

The previous prime is 135829. The next prime is 135841. The reversal of 135840 is 48531.

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 (135841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 339 + ... + 621.

It is an arithmetic number, because the mean of its divisors is an integer number (8946).

2¹³⁵⁸⁴⁰ is an apocalyptic number.

135840 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 135840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (214704).

135840 is an abundant number, since it is smaller than the sum of its proper divisors (293568).

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

135840 is a wasteful number, since it uses less digits than its factorization.

135840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 301 (or 293 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 135840 is about 368.5647839933. The cubic root of 135840 is about 51.4054569850.

The spelling of 135840 in words is "one hundred thirty-five thousand, eight hundred forty".