640824 has 16 divisors (see below), whose sum is σ = 1602120. Its totient is φ = 213600.

The previous prime is 640793. The next prime is 640837. The reversal of 640824 is 428046.

640824 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (24), and also a Moran number because the ratio is a prime number: 26701 = 640824 / (6 + 4 + 0 + 8 + 2 + 4).

It is a junction number, because it is equal to n+sod(n) for n = 640794 and 640803.

It is a congruent number.

It is an unprimeable number.

640824 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 3 ways as a sum of consecutive naturals, for example, 13327 + ... + 13374.

2⁶⁴⁰⁸²⁴ is an apocalyptic number.

It is an amenable number.

640824 is an abundant number, since it is smaller than the sum of its proper divisors (961296).

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

640824 is a wasteful number, since it uses less digits than its factorization.

640824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26710 (or 26706 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

The square root of 640824 is about 800.5148343410. The cubic root of 640824 is about 86.2143562023.

The spelling of 640824 in words is "six hundred forty thousand, eight hundred twenty-four".