12666640 has 40 divisors (see below), whose sum is σ = 33658560. Its totient is φ = 4342656.

The previous prime is 12666607. The next prime is 12666671. The reversal of 12666640 is 4666621.

12666640 = 294² + 295² + ... + 398².

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10750 + ... + 11869.

It is an arithmetic number, because the mean of its divisors is an integer number (841464).

Almost surely, 2^12666640 is an apocalyptic number.

12666640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

12666640 is an abundant number, since it is smaller than the sum of its proper divisors (20991920).

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

12666640 is a wasteful number, since it uses less digits than its factorization.

12666640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22639 (or 22633 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 12666640 is about 3559.0223376652. The cubic root of 12666640 is about 233.1061916558.

It can be divided in two parts, 126 and 66640, that added together give a palindrome (66766).

The spelling of 12666640 in words is "twelve million, six hundred sixty-six thousand, six hundred forty".