1636243109 has 2 divisors, whose sum is σ = 1636243110. Its totient is φ = 1636243108.

The previous prime is 1636243079. The next prime is 1636243111. The reversal of 1636243109 is 9013426361.

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., 1414888225 + 221354884 = 37615^2 + 14878^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1636243109 is a prime.

Together with 1636243111, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1636243909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 818121554 + 818121555.

It is an arithmetic number, because the mean of its divisors is an integer number (818121555).

Almost surely, 2^1636243109 is an apocalyptic number.

It is an amenable number.

1636243109 is a deficient number, since it is larger than the sum of its proper divisors (1).

1636243109 is an equidigital number, since it uses as much as digits as its factorization.

1636243109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 35.

The square root of 1636243109 is about 40450.5019622748. The cubic root of 1636243109 is about 1178.3725311386.

The spelling of 1636243109 in words is "one billion, six hundred thirty-six million, two hundred forty-three thousand, one hundred nine".