65640 has 32 divisors (see below), whose sum is σ = 197280. Its totient is φ = 17472.

The previous prime is 65633. The next prime is 65647. The reversal of 65640 is 4656.

It is an interprime number because it is at equal distance from previous prime (65633) and next prime (65647).

It is a zygodrome in base 9.

It is not an unprimeable number, because it can be changed into a prime (65647) by changing a digit.

65640 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, 154 + ... + 393.

It is an arithmetic number, because the mean of its divisors is an integer number (6165).

2⁶⁵⁶⁴⁰ is an apocalyptic number.

65640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

65640 is an abundant number, since it is smaller than the sum of its proper divisors (131640).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (98640).

65640 is a wasteful number, since it uses less digits than its factorization.

65640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 561 (or 557 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 65640 is about 256.2030444784. The cubic root of 65640 is about 40.3387891139.

It can be divided in two parts, 656 and 40, that added together give a palindrome (696).

The spelling of 65640 in words is "sixty-five thousand, six hundred forty".