12138102721 has 4 divisors (see below), whose sum is σ = 12205164244. Its totient is φ = 12071041200.

The previous prime is 12138102719. The next prime is 12138102727. The reversal of 12138102721 is 12720183121.

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 551733121 + 11586369600 = 23489^2 + 107640^2 .

It is a cyclic number.

It is not a de Polignac number, because 12138102721 - 2¹ = 12138102719 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 12138102721.

It is not an unprimeable number, because it can be changed into a prime (12138102727) 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, 33530490 + ... + 33530851.

It is an arithmetic number, because the mean of its divisors is an integer number (3051291061).

Almost surely, 2^12138102721 is an apocalyptic number.

It is an amenable number.

12138102721 is a deficient number, since it is larger than the sum of its proper divisors (67061523).

12138102721 is an equidigital number, since it uses as much as digits as its factorization.

12138102721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67061522.

The product of its (nonzero) digits is 1344, while the sum is 28.

Adding to 12138102721 its reverse (12720183121), we get a palindrome (24858285842).

The spelling of 12138102721 in words is "twelve billion, one hundred thirty-eight million, one hundred two thousand, seven hundred twenty-one".