6658640 has 20 divisors (see below), whose sum is σ = 15481524. Its totient is φ = 2663424.

The previous prime is 6658637. The next prime is 6658649. The reversal of 6658640 is 468566.

It can be written as a sum of positive squares in 2 ways, for example, as 4999696 + 1658944 = 2236^2 + 1288^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 6658640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6658649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41537 + ... + 41696.

Almost surely, 2^6658640 is an apocalyptic number.

It is an amenable number.

6658640 is an abundant number, since it is smaller than the sum of its proper divisors (8822884).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6658640 is a wasteful number, since it uses less digits than its factorization.

6658640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83246 (or 83240 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 35.

The square root of 6658640 is about 2580.4340720119. The cubic root of 6658640 is about 188.1316416164.

The spelling of 6658640 in words is "six million, six hundred fifty-eight thousand, six hundred forty".