1231131233209 has 2 divisors, whose sum is σ = 1231131233210. Its totient is φ = 1231131233208.

The previous prime is 1231131233207. The next prime is 1231131233237. The reversal of 1231131233209 is 9023321311321.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 680537552809 + 550593680400 = 824947^2 + 742020^2 .

It is an emirp because it is prime and its reverse (9023321311321) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1231131233209 - 2¹ = 1231131233207 is a prime.

It is a super-2 number, since 2×1231131233209² (a number of 25 digits) contains 22 as substring.

Together with 1231131233207, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1231131233207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615565616604 + 615565616605.

It is an arithmetic number, because the mean of its divisors is an integer number (615565616605).

Almost surely, 2^{1231131233209} is an apocalyptic number.

It is an amenable number.

1231131233209 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231131233209 is an equidigital number, since it uses as much as digits as its factorization.

1231131233209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5832, while the sum is 31.

The spelling of 1231131233209 in words is "one trillion, two hundred thirty-one billion, one hundred thirty-one million, two hundred thirty-three thousand, two hundred nine".