1312391538 has 16 divisors (see below), whose sum is σ = 2916425760. Its totient is φ = 437463828.

The previous prime is 1312391533. The next prime is 1312391543. The reversal of 1312391538 is 8351932131.

1312391538 is a `hidden beast` number, since 1 + 31 + 2 + 3 + 91 + 538 = 666.

It is an interprime number because it is at equal distance from previous prime (1312391533) and next prime (1312391543).

It is not an unprimeable number, because it can be changed into a prime (1312391533) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12151720 + ... + 12151827.

It is an arithmetic number, because the mean of its divisors is an integer number (182276610).

Almost surely, 2^1312391538 is an apocalyptic number.

1312391538 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1312391538 is an abundant number, since it is smaller than the sum of its proper divisors (1604034222).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1312391538 is a wasteful number, since it uses less digits than its factorization.

1312391538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24303558 (or 24303552 counting only the distinct ones).

The product of its digits is 19440, while the sum is 36.

The square root of 1312391538 is about 36226.9449167329. The cubic root of 1312391538 is about 1094.8496246869.

The spelling of 1312391538 in words is "one billion, three hundred twelve million, three hundred ninety-one thousand, five hundred thirty-eight".