640490 has 16 divisors (see below), whose sum is σ = 1213920. Its totient is φ = 242640.

The previous prime is 640483. The next prime is 640499. The reversal of 640490 is 94046.

It is not an unprimeable number, because it can be changed into a prime (640499) 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 7 ways as a sum of consecutive naturals, for example, 1496 + ... + 1875.

It is an arithmetic number, because the mean of its divisors is an integer number (75870).

2⁶⁴⁰⁴⁹⁰ is an apocalyptic number.

640490 is a deficient number, since it is larger than the sum of its proper divisors (573430).

640490 is a wasteful number, since it uses less digits than its factorization.

640490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3397.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 640490 is about 800.3061914043. The cubic root of 640490 is about 86.1993751783.

It can be divided in two parts, 640 and 490, that multiplied together give a square (313600 = 560²).

The spelling of 640490 in words is "six hundred forty thousand, four hundred ninety".