640748 has 12 divisors (see below), whose sum is σ = 1148952. Its totient is φ = 312480.

The previous prime is 640741. The next prime is 640771. The reversal of 640748 is 847046.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 640748.

It is not an unprimeable number, because it can be changed into a prime (640741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1790 + ... + 2117.

It is an arithmetic number, because the mean of its divisors is an integer number (95746).

2⁶⁴⁰⁷⁴⁸ is an apocalyptic number.

It is an amenable number.

640748 is a deficient number, since it is larger than the sum of its proper divisors (508204).

640748 is a wasteful number, since it uses less digits than its factorization.

640748 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3952 (or 3950 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 29.

The square root of 640748 is about 800.4673634821. The cubic root of 640748 is about 86.2109478041.

The spelling of 640748 in words is "six hundred forty thousand, seven hundred forty-eight".