1243520009 has 2 divisors, whose sum is σ = 1243520010. Its totient is φ = 1243520008.

The previous prime is 1243519951. The next prime is 1243520011. The reversal of 1243520009 is 9000253421.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1192182784 + 51337225 = 34528^2 + 7165^2 .

It is an emirp because it is prime and its reverse (9000253421) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1243520009 - 2²⁸ = 975084553 is a prime.

It is a Sophie Germain prime.

Together with 1243520011, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1243520009.

It is not a weakly prime, because it can be changed into another prime (1243520039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 621760004 + 621760005.

It is an arithmetic number, because the mean of its divisors is an integer number (621760005).

Almost surely, 2^1243520009 is an apocalyptic number.

It is an amenable number.

1243520009 is a deficient number, since it is larger than the sum of its proper divisors (1).

1243520009 is an equidigital number, since it uses as much as digits as its factorization.

1243520009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 1243520009 is about 35263.5790724651. The cubic root of 1243520009 is about 1075.3526901885.

The spelling of 1243520009 in words is "one billion, two hundred forty-three million, five hundred twenty thousand, nine".