640208 has 10 divisors (see below), whose sum is σ = 1240434. Its totient is φ = 320096.

The previous prime is 640193. The next prime is 640219. The reversal of 640208 is 802046.

It can be written as a sum of positive squares in only one way, i.e., 529984 + 110224 = 728^2 + 332^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 640208.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19991 + ... + 20022.

2⁶⁴⁰²⁰⁸ is an apocalyptic number.

It is an amenable number.

640208 is a deficient number, since it is larger than the sum of its proper divisors (600226).

640208 is a wasteful number, since it uses less digits than its factorization.

640208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40021 (or 40015 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 640208 is about 800.1299894392. The cubic root of 640208 is about 86.1867224737.

It can be divided in two parts, 640 and 208, that added together give a palindrome (848).

The spelling of 640208 in words is "six hundred forty thousand, two hundred eight".