640281 has 16 divisors (see below), whose sum is σ = 921600. Its totient is φ = 394128.

The previous prime is 640279. The next prime is 640303. The reversal of 640281 is 182046.

It is not a de Polignac number, because 640281 - 2¹ = 640279 is a prime.

It is a super-3 number, since 3×640281³ = 787468333281924123, which contains 333 as substring. Note that it is a super-d number also for d = 2.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640281.

It is not an unprimeable number, because it can be changed into a prime (640231) 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, 2560 + ... + 2798.

It is an arithmetic number, because the mean of its divisors is an integer number (57600).

2⁶⁴⁰²⁸¹ is an apocalyptic number.

It is an amenable number.

640281 is a deficient number, since it is larger than the sum of its proper divisors (281319).

640281 is a wasteful number, since it uses less digits than its factorization.

640281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 640281 is about 800.1756057266. The cubic root of 640281 is about 86.1899981756.

The spelling of 640281 in words is "six hundred forty thousand, two hundred eighty-one".