12820042409 has 2 divisors, whose sum is σ = 12820042410. Its totient is φ = 12820042408.

The previous prime is 12820042357. The next prime is 12820042447. The reversal of 12820042409 is 90424002821.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11433597184 + 1386445225 = 106928^2 + 37235^2 .

It is an emirp because it is prime and its reverse (90424002821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12820042409 - 2²⁰ = 12818993833 is a prime.

It is not a weakly prime, because it can be changed into another prime (12820042309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6410021204 + 6410021205.

It is an arithmetic number, because the mean of its divisors is an integer number (6410021205).

Almost surely, 2^12820042409 is an apocalyptic number.

It is an amenable number.

12820042409 is a deficient number, since it is larger than the sum of its proper divisors (1).

12820042409 is an equidigital number, since it uses as much as digits as its factorization.

12820042409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 32.

The spelling of 12820042409 in words is "twelve billion, eight hundred twenty million, forty-two thousand, four hundred nine".