1312155981 has 6 divisors (see below), whose sum is σ = 1895336430. Its totient is φ = 874770648.

The previous prime is 1312155973. The next prime is 1312155983. The reversal of 1312155981 is 1895512131.

1312155981 is a `hidden beast` number, since 1 + 3 + 1 + 21 + 559 + 81 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1298160900 + 13995081 = 36030^2 + 3741^2 .

It is not a de Polignac number, because 1312155981 - 2³ = 1312155973 is a prime.

It is a super-2 number, since 2×1312155981² = 3443506636948144722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1312155983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 72897546 + ... + 72897563.

It is an arithmetic number, because the mean of its divisors is an integer number (315889405).

Almost surely, 2^1312155981 is an apocalyptic number.

It is an amenable number.

1312155981 is a deficient number, since it is larger than the sum of its proper divisors (583180449).

1312155981 is a wasteful number, since it uses less digits than its factorization.

1312155981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145795115 (or 145795112 counting only the distinct ones).

The product of its digits is 10800, while the sum is 36.

The square root of 1312155981 is about 36223.6936410411. The cubic root of 1312155981 is about 1094.7841170705.

The spelling of 1312155981 in words is "one billion, three hundred twelve million, one hundred fifty-five thousand, nine hundred eighty-one".