1291319440 has 20 divisors (see below), whose sum is σ = 3002317884. Its totient is φ = 516527744.

The previous prime is 1291319339. The next prime is 1291319459. The reversal of 1291319440 is 449131921.

It can be written as a sum of positive squares in 2 ways, for example, as 402564096 + 888755344 = 20064^2 + 29812^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×1291319440² = 3335011792243827200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1291319396 and 1291319405.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 8070667 + ... + 8070826.

Almost surely, 2^1291319440 is an apocalyptic number.

1291319440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1291319440 is an abundant number, since it is smaller than the sum of its proper divisors (1710998444).

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

1291319440 is a wasteful number, since it uses less digits than its factorization.

1291319440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16141506 (or 16141500 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 1291319440 is about 35934.9334213937. The cubic root of 1291319440 is about 1088.9582505371.

The spelling of 1291319440 in words is "one billion, two hundred ninety-one million, three hundred nineteen thousand, four hundred forty".