1231001209 has 2 divisors, whose sum is σ = 1231001210. Its totient is φ = 1231001208.

The previous prime is 1231001207. The next prime is 1231001243. The reversal of 1231001209 is 9021001321.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1051575184 + 179426025 = 32428^2 + 13395^2 .

It is an emirp because it is prime and its reverse (9021001321) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1231001209 - 2¹ = 1231001207 is a prime.

Together with 1231001207, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1231001207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615500604 + 615500605.

It is an arithmetic number, because the mean of its divisors is an integer number (615500605).

Almost surely, 2^1231001209 is an apocalyptic number.

It is an amenable number.

1231001209 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231001209 is an equidigital number, since it uses as much as digits as its factorization.

1231001209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 1231001209 is about 35085.6268149794. The cubic root of 1231001209 is about 1071.7319053839.

The spelling of 1231001209 in words is "one billion, two hundred thirty-one million, one thousand, two hundred nine".