6640281 has 6 divisors (see below), whose sum is σ = 9591530. Its totient is φ = 4426848.

The previous prime is 6640241. The next prime is 6640289. The reversal of 6640281 is 1820466.

It can be written as a sum of positive squares in only one way, i.e., 4064256 + 2576025 = 2016^2 + 1605^2 .

It is not a de Polignac number, because 6640281 - 2⁹ = 6639769 is a prime.

It is a super-2 number, since 2×6640281² = 88186663517922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6640289) 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 5 ways as a sum of consecutive naturals, for example, 368896 + ... + 368913.

Almost surely, 2^6640281 is an apocalyptic number.

It is an amenable number.

6640281 is a deficient number, since it is larger than the sum of its proper divisors (2951249).

6640281 is a wasteful number, since it uses less digits than its factorization.

6640281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 737815 (or 737812 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 6640281 is about 2576.8742693426. The cubic root of 6640281 is about 187.9585788480.

The spelling of 6640281 in words is "six million, six hundred forty thousand, two hundred eighty-one".