12751221 has 12 divisors (see below), whose sum is σ = 19777632. Its totient is φ = 7286328.

The previous prime is 12751201. The next prime is 12751231. The reversal of 12751221 is 12215721.

It is not a de Polignac number, because 12751221 - 2⁶ = 12751157 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12751201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43225 + ... + 43518.

It is an arithmetic number, because the mean of its divisors is an integer number (1648136).

Almost surely, 2^12751221 is an apocalyptic number.

It is an amenable number.

12751221 is a deficient number, since it is larger than the sum of its proper divisors (7026411).

12751221 is an equidigital number, since it uses as much as digits as its factorization.

12751221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86760 (or 86753 counting only the distinct ones).

The product of its digits is 280, while the sum is 21.

The square root of 12751221 is about 3570.8851843766. The cubic root of 12751221 is about 233.6238935828.

Adding to 12751221 its reverse (12215721), we get a palindrome (24966942).

The spelling of 12751221 in words is "twelve million, seven hundred fifty-one thousand, two hundred twenty-one".