12566021 has 4 divisors (see below), whose sum is σ = 13532652. Its totient is φ = 11599392.

The previous prime is 12566003. The next prime is 12566023. The reversal of 12566021 is 12066521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12066521 = 71 ⋅169951.

It can be written as a sum of positive squares in 2 ways, for example, as 4669921 + 7896100 = 2161^2 + 2810^2 .

It is a cyclic number.

It is not a de Polignac number, because 12566021 - 2¹⁸ = 12303877 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12566023) 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, 483296 + ... + 483321.

It is an arithmetic number, because the mean of its divisors is an integer number (3383163).

Almost surely, 2^12566021 is an apocalyptic number.

It is an amenable number.

12566021 is a deficient number, since it is larger than the sum of its proper divisors (966631).

12566021 is an equidigital number, since it uses as much as digits as its factorization.

12566021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 966630.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 12566021 is about 3544.8583892731. The cubic root of 12566021 is about 232.4873142190.

Subtracting from 12566021 its reverse (12066521), we obtain a triangular number (499500 = T₉₉₉).

The spelling of 12566021 in words is "twelve million, five hundred sixty-six thousand, twenty-one".