1231355221609 has 2 divisors, whose sum is σ = 1231355221610. Its totient is φ = 1231355221608.

The previous prime is 1231355221597. The next prime is 1231355221633. The reversal of 1231355221609 is 9061225531321.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 854463594384 + 376891627225 = 924372^2 + 613915^2 .

It is a cyclic number.

It is not a de Polignac number, because 1231355221609 - 2⁹ = 1231355221097 is a prime.

It is not a weakly prime, because it can be changed into another prime (1231355221699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615677610804 + 615677610805.

It is an arithmetic number, because the mean of its divisors is an integer number (615677610805).

Almost surely, 2^{1231355221609} is an apocalyptic number.

It is an amenable number.

1231355221609 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231355221609 is an equidigital number, since it uses as much as digits as its factorization.

1231355221609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 97200, while the sum is 40.

The spelling of 1231355221609 in words is "one trillion, two hundred thirty-one billion, three hundred fifty-five million, two hundred twenty-one thousand, six hundred nine".