12543721667 has 2 divisors, whose sum is σ = 12543721668. Its totient is φ = 12543721666.

The previous prime is 12543721639. The next prime is 12543721681. The reversal of 12543721667 is 76612734521.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 12543721667 - 2¹⁶ = 12543656131 is a prime.

It is not a weakly prime, because it can be changed into another prime (12543721637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6271860833 + 6271860834.

It is an arithmetic number, because the mean of its divisors is an integer number (6271860834).

Almost surely, 2^12543721667 is an apocalyptic number.

12543721667 is a deficient number, since it is larger than the sum of its proper divisors (1).

12543721667 is an equidigital number, since it uses as much as digits as its factorization.

12543721667 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 423360, while the sum is 44.

The spelling of 12543721667 in words is "twelve billion, five hundred forty-three million, seven hundred twenty-one thousand, six hundred sixty-seven".