12912198721 has 4 divisors (see below), whose sum is σ = 12913264944. Its totient is φ = 12911132500.

The previous prime is 12912198701. The next prime is 12912198727. The reversal of 12912198721 is 12789121921.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12789121921 = 113089².

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12912198721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12912198727) 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, 514735 + ... + 539236.

It is an arithmetic number, because the mean of its divisors is an integer number (3228316236).

Almost surely, 2^12912198721 is an apocalyptic number.

It is an amenable number.

12912198721 is a deficient number, since it is larger than the sum of its proper divisors (1066223).

12912198721 is a wasteful number, since it uses less digits than its factorization.

12912198721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1066222.

The product of its digits is 36288, while the sum is 43.

The spelling of 12912198721 in words is "twelve billion, nine hundred twelve million, one hundred ninety-eight thousand, seven hundred twenty-one".