12640661 has 4 divisors (see below), whose sum is σ = 13789824. Its totient is φ = 11491500.

The previous prime is 12640657. The next prime is 12640687. The reversal of 12640661 is 16604621.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 12640661 - 2² = 12640657 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 12640661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12640601) 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, 574565 + ... + 574586.

It is an arithmetic number, because the mean of its divisors is an integer number (3447456).

Almost surely, 2^12640661 is an apocalyptic number.

12640661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

12640661 is a deficient number, since it is larger than the sum of its proper divisors (1149163).

12640661 is a wasteful number, since it uses less digits than its factorization.

12640661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1149162.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 12640661 is about 3555.3707260988. The cubic root of 12640661 is about 232.9467173563.

The spelling of 12640661 in words is "twelve million, six hundred forty thousand, six hundred sixty-one".