242640 has 60 divisors (see below), whose sum is σ = 817284. Its totient is φ = 64512.

The previous prime is 242639. The next prime is 242647. The reversal of 242640 is 46242.

242640 is a `hidden beast` number, since 24 + 2 + 640 = 666.

242640 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 76176 + 166464 = 276^2 + 408^2 .

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

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

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (242647) 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, 552 + ... + 888.

2²⁴²⁶⁴⁰ is an apocalyptic number.

242640 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 242640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (408642).

242640 is an abundant number, since it is smaller than the sum of its proper divisors (574644).

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

242640 is a wasteful number, since it uses less digits than its factorization.

242640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356 (or 347 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 242640 is about 492.5850180426. The cubic root of 242640 is about 62.3716834046.

Adding to 242640 its reverse (46242), we get a palindrome (288882).

The spelling of 242640 in words is "two hundred forty-two thousand, six hundred forty".