1291865487 has 8 divisors (see below), whose sum is σ = 1879077120. Its totient is φ = 782948760.

The previous prime is 1291865483. The next prime is 1291865489. The reversal of 1291865487 is 7845681921.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1291865487 - 2² = 1291865483 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1291865483) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19573687 + ... + 19573752.

It is an arithmetic number, because the mean of its divisors is an integer number (234884640).

Almost surely, 2^1291865487 is an apocalyptic number.

1291865487 is a deficient number, since it is larger than the sum of its proper divisors (587211633).

1291865487 is a wasteful number, since it uses less digits than its factorization.

1291865487 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39147453.

The product of its digits is 967680, while the sum is 51.

The square root of 1291865487 is about 35942.5303366360. The cubic root of 1291865487 is about 1089.1117211071. Note that the first 3 decimals are identical.

The spelling of 1291865487 in words is "one billion, two hundred ninety-one million, eight hundred sixty-five thousand, four hundred eighty-seven".