6640660 has 24 divisors (see below), whose sum is σ = 15018696. Its totient is φ = 2451840.

The previous prime is 6640657. The next prime is 6640663. The reversal of 6640660 is 660466.

It is an interprime number because it is at equal distance from previous prime (6640657) and next prime (6640663).

It can be written as a sum of positive squares in 4 ways, for example, as 66564 + 6574096 = 258^2 + 2564^2 .

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6640663) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12511 + ... + 13030.

It is an arithmetic number, because the mean of its divisors is an integer number (625779).

Almost surely, 2^6640660 is an apocalyptic number.

It is an amenable number.

6640660 is an abundant number, since it is smaller than the sum of its proper divisors (8378036).

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

6640660 is a wasteful number, since it uses less digits than its factorization.

6640660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25563 (or 25561 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 6640660 is about 2576.9478069996. The cubic root of 6640660 is about 187.9621547482.

It can be divided in two parts, 66406 and 60, that added together give a palindrome (66466).

The spelling of 6640660 in words is "six million, six hundred forty thousand, six hundred sixty".