12636221 has 4 divisors (see below), whose sum is σ = 13608252. Its totient is φ = 11664192.

The previous prime is 12636209. The next prime is 12636229. The reversal of 12636221 is 12263621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12263621 = 277 ⋅44273.

It can be written as a sum of positive squares in 2 ways, for example, as 5692996 + 6943225 = 2386^2 + 2635^2 .

It is a cyclic number.

It is not a de Polignac number, because 12636221 - 2¹⁸ = 12374077 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 (12636229) 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, 485996 + ... + 486021.

It is an arithmetic number, because the mean of its divisors is an integer number (3402063).

Almost surely, 2^12636221 is an apocalyptic number.

It is an amenable number.

12636221 is a deficient number, since it is larger than the sum of its proper divisors (972031).

12636221 is an equidigital number, since it uses as much as digits as its factorization.

12636221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 972030.

The product of its digits is 864, while the sum is 23.

The square root of 12636221 is about 3554.7462638000. The cubic root of 12636221 is about 232.9194401818.

Adding to 12636221 its reverse (12263621), we get a palindrome (24899842).

The spelling of 12636221 in words is "twelve million, six hundred thirty-six thousand, two hundred twenty-one".