640585 has 16 divisors (see below), whose sum is σ = 884160. Its totient is φ = 440640.

The previous prime is 640583. The next prime is 640589. The reversal of 640585 is 585046.

640585 = 123² + 124² + ... + 155².

It is not a de Polignac number, because 640585 - 2¹ = 640583 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640583) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 739 + ... + 1351.

It is an arithmetic number, because the mean of its divisors is an integer number (55260).

2⁶⁴⁰⁵⁸⁵ is an apocalyptic number.

It is an amenable number.

640585 is a deficient number, since it is larger than the sum of its proper divisors (243575).

640585 is a wasteful number, since it uses less digits than its factorization.

640585 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 648.

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 640585 is about 800.3655414871. The cubic root of 640585 is about 86.2036367779.

It can be divided in two parts, 640 and 585, that added together give a triangular number (1225 = T₄₉).

The spelling of 640585 in words is "six hundred forty thousand, five hundred eighty-five".