12721105 has 4 divisors (see below), whose sum is σ = 15265332. Its totient is φ = 10176880.

The previous prime is 12721103. The next prime is 12721147. The reversal of 12721105 is 50112721.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10086976 + 2634129 = 3176^2 + 1623^2 .

It is not a de Polignac number, because 12721105 - 2¹ = 12721103 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12721103) 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 3 ways as a sum of consecutive naturals, for example, 1272106 + ... + 1272115.

It is an arithmetic number, because the mean of its divisors is an integer number (3816333).

Almost surely, 2^12721105 is an apocalyptic number.

It is an amenable number.

12721105 is a deficient number, since it is larger than the sum of its proper divisors (2544227).

12721105 is an equidigital number, since it uses as much as digits as its factorization.

12721105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2544226.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 12721105 is about 3566.6658099687. The cubic root of 12721105 is about 233.4398232742.

Adding to 12721105 its reverse (50112721), we get a palindrome (62833826).

The spelling of 12721105 in words is "twelve million, seven hundred twenty-one thousand, one hundred five".