1311255521 has 2 divisors, whose sum is σ = 1311255522. Its totient is φ = 1311255520.

The previous prime is 1311255511. The next prime is 1311255523. The reversal of 1311255521 is 1255521131.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1132659025 + 178596496 = 33655^2 + 13364^2 .

It is a cyclic number.

It is not a de Polignac number, because 1311255521 - 2¹⁸ = 1310993377 is a prime.

Together with 1311255523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1311255523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 655627760 + 655627761.

It is an arithmetic number, because the mean of its divisors is an integer number (655627761).

Almost surely, 2^1311255521 is an apocalyptic number.

It is an amenable number.

1311255521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1311255521 is an equidigital number, since it uses as much as digits as its factorization.

1311255521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1500, while the sum is 26.

The square root of 1311255521 is about 36211.2623502689. The cubic root of 1311255521 is about 1094.5336298549.

Adding to 1311255521 its reverse (1255521131), we get a palindrome (2566776652).

The spelling of 1311255521 in words is "one billion, three hundred eleven million, two hundred fifty-five thousand, five hundred twenty-one".