1231305511 has 2 divisors, whose sum is σ = 1231305512. Its totient is φ = 1231305510.

The previous prime is 1231305497. The next prime is 1231305521. The reversal of 1231305511 is 1155031321.

It is a strong prime.

It is an emirp because it is prime and its reverse (1155031321) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1231305511 - 2⁵ = 1231305479 is a prime.

It is a super-2 number, since 2×1231305511² = 3032226522837942242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1231305521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615652755 + 615652756.

It is an arithmetic number, because the mean of its divisors is an integer number (615652756).

Almost surely, 2^1231305511 is an apocalyptic number.

1231305511 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231305511 is an equidigital number, since it uses as much as digits as its factorization.

1231305511 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 450, while the sum is 22.

The square root of 1231305511 is about 35089.9631091285. The cubic root of 1231305511 is about 1071.8202083822.

Adding to 1231305511 its reverse (1155031321), we get a palindrome (2386336832).

The spelling of 1231305511 in words is "one billion, two hundred thirty-one million, three hundred five thousand, five hundred eleven".