640498 has 8 divisors (see below), whose sum is σ = 964908. Its totient is φ = 318864.

The previous prime is 640483. The next prime is 640499. The reversal of 640498 is 894046.

It can be written as a sum of positive squares in 2 ways, for example, as 431649 + 208849 = 657^2 + 457^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

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 3 ways as a sum of consecutive naturals, for example, 40 + ... + 1132.

2⁶⁴⁰⁴⁹⁸ is an apocalyptic number.

640498 is a deficient number, since it is larger than the sum of its proper divisors (324410).

640498 is a wasteful number, since it uses less digits than its factorization.

640498 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1388.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 640498 is about 800.3111894757. The cubic root of 640498 is about 86.1997340661.

It can be divided in two parts, 6 and 40498, that added together give a palindrome (40504).

The spelling of 640498 in words is "six hundred forty thousand, four hundred ninety-eight".