42640 has 40 divisors (see below), whose sum is σ = 109368. Its totient is φ = 15360.

The previous prime is 42611. The next prime is 42641. The reversal of 42640 is 4624.

42640 = 10² + 11² + ... + 50².

It can be written as a sum of positive squares in 4 ways, for example, as 1024 + 41616 = 32^2 + 204^2 .

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

It is a hoax number, since the sum of its digits (16) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a plaindrome in base 14.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 42640.

It is not an unprimeable number, because it can be changed into a prime (42641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1020 + ... + 1060.

2⁴²⁶⁴⁰ is an apocalyptic number.

42640 is a gapful number since it is divisible by the number (40) 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 42640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (54684).

42640 is an abundant number, since it is smaller than the sum of its proper divisors (66728).

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

42640 is a wasteful number, since it uses less digits than its factorization.

42640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67 (or 61 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 42640 is about 206.4945519862. The cubic root of 42640 is about 34.9359372351.

Subtracting from 42640 its sum of digits (16), we obtain a palindrome (42624).

The spelling of 42640 in words is "forty-two thousand, six hundred forty".