12921661 has 4 divisors (see below), whose sum is σ = 13054972. Its totient is φ = 12788352.

The previous prime is 12921613. The next prime is 12921673. The reversal of 12921661 is 16612921.

12921661 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9703225 + 3218436 = 3115^2 + 1794^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12921661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12921611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66510 + ... + 66703.

It is an arithmetic number, because the mean of its divisors is an integer number (3263743).

Almost surely, 2^12921661 is an apocalyptic number.

It is an amenable number.

12921661 is a deficient number, since it is larger than the sum of its proper divisors (133311).

12921661 is an equidigital number, since it uses as much as digits as its factorization.

12921661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133310.

The product of its digits is 1296, while the sum is 28.

The square root of 12921661 is about 3594.6711949774. The cubic root of 12921661 is about 234.6602060660.

The spelling of 12921661 in words is "twelve million, nine hundred twenty-one thousand, six hundred sixty-one".