1242143209 has 2 divisors, whose sum is σ = 1242143210. Its totient is φ = 1242143208.

The previous prime is 1242143207. The next prime is 1242143251. The reversal of 1242143209 is 9023412421.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1067982400 + 174160809 = 32680^2 + 13197^2 .

It is an emirp because it is prime and its reverse (9023412421) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1242143209 - 2¹ = 1242143207 is a prime.

Together with 1242143207, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1242143207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 621071604 + 621071605.

It is an arithmetic number, because the mean of its divisors is an integer number (621071605).

Almost surely, 2^1242143209 is an apocalyptic number.

It is an amenable number.

1242143209 is a deficient number, since it is larger than the sum of its proper divisors (1).

1242143209 is an equidigital number, since it uses as much as digits as its factorization.

1242143209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 1242143209 is about 35244.0521081217. The cubic root of 1242143209 is about 1074.9556741053.

The spelling of 1242143209 in words is "one billion, two hundred forty-two million, one hundred forty-three thousand, two hundred nine".