6663865 has 16 divisors (see below), whose sum is σ = 8679888. Its totient is φ = 4882176.

The previous prime is 6663863. The next prime is 6663869. The reversal of 6663865 is 5683666.

It can be written as a sum of positive squares in 8 ways, for example, as 1610361 + 5053504 = 1269^2 + 2248^2 .

It is not a de Polignac number, because 6663865 - 2¹ = 6663863 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6663863) 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, 9879 + ... + 10531.

It is an arithmetic number, because the mean of its divisors is an integer number (542493).

Almost surely, 2^6663865 is an apocalyptic number.

6663865 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

6663865 is a deficient number, since it is larger than the sum of its proper divisors (2016023).

6663865 is a wasteful number, since it uses less digits than its factorization.

6663865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 828.

The product of its digits is 155520, while the sum is 40.

The square root of 6663865 is about 2581.4463000419. The cubic root of 6663865 is about 188.1808373893.

The spelling of 6663865 in words is "six million, six hundred sixty-three thousand, eight hundred sixty-five".