12555221 has 12 divisors (see below), whose sum is σ = 14676588. Its totient is φ = 10708992.

The previous prime is 12555199. The next prime is 12555241. The reversal of 12555221 is 12255521.

It can be written as a sum of positive squares in 2 ways, for example, as 11764900 + 790321 = 3430^2 + 889^2 .

It is not a de Polignac number, because 12555221 - 2¹⁸ = 12293077 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 (12555241) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12095 + ... + 13091.

It is an arithmetic number, because the mean of its divisors is an integer number (1223049).

Almost surely, 2^12555221 is an apocalyptic number.

It is an amenable number.

12555221 is a deficient number, since it is larger than the sum of its proper divisors (2121367).

12555221 is an equidigital number, since it uses as much as digits as its factorization.

12555221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1268 (or 1261 counting only the distinct ones).

The product of its digits is 1000, while the sum is 23.

The square root of 12555221 is about 3543.3347287548. The cubic root of 12555221 is about 232.4206905661.

The spelling of 12555221 in words is "twelve million, five hundred fifty-five thousand, two hundred twenty-one".