245640 has 64 divisors (see below), whose sum is σ = 777600. Its totient is φ = 61952.

The previous prime is 245639. The next prime is 245653. The reversal of 245640 is 46542.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2716 + ... + 2804.

It is an arithmetic number, because the mean of its divisors is an integer number (12150).

245640 is a Friedman number, since it can be written as 60*(4*4^5-2), using all its digits and the basic arithmetic operations.

2²⁴⁵⁶⁴⁰ is an apocalyptic number.

245640 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 245640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (388800).

245640 is an abundant number, since it is smaller than the sum of its proper divisors (531960).

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

245640 is a wasteful number, since it uses less digits than its factorization.

245640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126 (or 122 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 245640 is about 495.6208228071. The cubic root of 245640 is about 62.6276856311.

The spelling of 245640 in words is "two hundred forty-five thousand, six hundred forty".