1331261388 has 18 divisors (see below), whose sum is σ = 3365133044. Its totient is φ = 443753784.

The previous prime is 1331261387. The next prime is 1331261411. The reversal of 1331261388 is 8831621331.

1331261388 is a `hidden beast` number, since 1 + 3 + 31 + 2 + 613 + 8 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 36979483 = 1331261388 / (1 + 3 + 3 + 1 + 2 + 6 + 1 + 3 + 8 + 8).

It is not an unprimeable number, because it can be changed into a prime (1331261387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 18489706 + ... + 18489777.

Almost surely, 2^1331261388 is an apocalyptic number.

1331261388 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1331261388 is an abundant number, since it is smaller than the sum of its proper divisors (2033871656).

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

1331261388 is a wasteful number, since it uses less digits than its factorization.

1331261388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36979493 (or 36979488 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 1331261388 is about 36486.4548565629. The cubic root of 1331261388 is about 1100.0720030003.

The spelling of 1331261388 in words is "one billion, three hundred thirty-one million, two hundred sixty-one thousand, three hundred eighty-eight".