1311123551 has 4 divisors (see below), whose sum is σ = 1312372104. Its totient is φ = 1309875000.

The previous prime is 1311123493. The next prime is 1311123571. The reversal of 1311123551 is 1553211131.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1311123551 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1311123571) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 622700 + ... + 624801.

It is an arithmetic number, because the mean of its divisors is an integer number (328093026).

Almost surely, 2^1311123551 is an apocalyptic number.

1311123551 is a deficient number, since it is larger than the sum of its proper divisors (1248553).

1311123551 is a wasteful number, since it uses less digits than its factorization.

1311123551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1248552.

The product of its digits is 450, while the sum is 23.

The square root of 1311123551 is about 36209.4400812827. The cubic root of 1311123551 is about 1094.4969092089.

Adding to 1311123551 its reverse (1553211131), we get a palindrome (2864334682).

The spelling of 1311123551 in words is "one billion, three hundred eleven million, one hundred twenty-three thousand, five hundred fifty-one".