6561666 has 12 divisors (see below), whose sum is σ = 14216982. Its totient is φ = 2187216.

The previous prime is 6561649. The next prime is 6561673. The reversal of 6561666 is 6661656.

It can be written as a sum of positive squares in only one way, i.e., 5157441 + 1404225 = 2271^2 + 1185^2 .

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 6561666.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 182251 + ... + 182286.

Almost surely, 2^6561666 is an apocalyptic number.

6561666 is an abundant number, since it is smaller than the sum of its proper divisors (7655316).

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

6561666 is a wasteful number, since it uses less digits than its factorization.

6561666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 364545 (or 364542 counting only the distinct ones).

The product of its digits is 38880, while the sum is 36.

The square root of 6561666 is about 2561.5749061856. The cubic root of 6561666 is about 187.2138782720.

It can be divided in two parts, 6561 and 666, that added together give a palindrome (7227).

The spelling of 6561666 in words is "six million, five hundred sixty-one thousand, six hundred sixty-six".