640269 has 12 divisors (see below), whose sum is σ = 1057056. Its totient is φ = 365832.

The previous prime is 640267. The next prime is 640279. The reversal of 640269 is 962046.

It is not a de Polignac number, because 640269 - 2¹ = 640267 is a prime.

It is a super-2 number, since 2×640269² = 819888784722, which contains 22 as substring.

It is an Ulam number.

640269 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640261) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5019 + ... + 5144.

It is an arithmetic number, because the mean of its divisors is an integer number (88088).

2⁶⁴⁰²⁶⁹ is an apocalyptic number.

It is an amenable number.

640269 is a deficient number, since it is larger than the sum of its proper divisors (416787).

640269 is a wasteful number, since it uses less digits than its factorization.

640269 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10176 (or 10173 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 640269 is about 800.1681073375. The cubic root of 640269 is about 86.1894597212.

It can be divided in two parts, 640 and 269, that added together give a palindrome (909).

The spelling of 640269 in words is "six hundred forty thousand, two hundred sixty-nine".