1311721756 has 12 divisors (see below), whose sum is σ = 2299537240. Its totient is φ = 654711120.

The previous prime is 1311721729. The next prime is 1311721757. The reversal of 1311721756 is 6571271131.

It is a happy number.

It is a super-2 number, since 2×1311721756² = 3441227930327447072, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1311721757) 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, 284871 + ... + 289438.

Almost surely, 2^1311721756 is an apocalyptic number.

It is an amenable number.

1311721756 is a deficient number, since it is larger than the sum of its proper divisors (987815484).

1311721756 is a wasteful number, since it uses less digits than its factorization.

1311721756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 574884 (or 574882 counting only the distinct ones).

The product of its digits is 8820, while the sum is 34.

The square root of 1311721756 is about 36217.6994851965. The cubic root of 1311721756 is about 1094.6633399961.

Adding to 1311721756 its reverse (6571271131), we get a palindrome (7882992887).

The spelling of 1311721756 in words is "one billion, three hundred eleven million, seven hundred twenty-one thousand, seven hundred fifty-six".