12521661 has 4 divisors (see below), whose sum is σ = 16695552. Its totient is φ = 8347772.

The previous prime is 12521623. The next prime is 12521669. The reversal of 12521661 is 16612521.

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 12521661 - 2⁹ = 12521149 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12521669) 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, 2086941 + ... + 2086946.

It is an arithmetic number, because the mean of its divisors is an integer number (4173888).

Almost surely, 2^12521661 is an apocalyptic number.

It is an amenable number.

12521661 is a deficient number, since it is larger than the sum of its proper divisors (4173891).

12521661 is an equidigital number, since it uses as much as digits as its factorization.

12521661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4173890.

The product of its digits is 720, while the sum is 24.

The square root of 12521661 is about 3538.5959079838. The cubic root of 12521661 is about 232.2134195955.

The spelling of 12521661 in words is "twelve million, five hundred twenty-one thousand, six hundred sixty-one".