245840 has 40 divisors (see below), whose sum is σ = 654720. Its totient is φ = 84096.

The previous prime is 245821. The next prime is 245849. The reversal of 245840 is 48542.

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

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (245849) by changing a digit.

245840 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, 341 + ... + 779.

It is an arithmetic number, because the mean of its divisors is an integer number (16368).

2²⁴⁵⁸⁴⁰ is an apocalyptic number.

245840 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 245840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (327360).

245840 is an abundant number, since it is smaller than the sum of its proper divisors (408880).

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

245840 is a wasteful number, since it uses less digits than its factorization.

245840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 459 (or 453 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 23.

The square root of 245840 is about 495.8225489023. The cubic root of 245840 is about 62.6446781666.

The spelling of 245840 in words is "two hundred forty-five thousand, eight hundred forty".