1321391887 has 4 divisors (see below), whose sum is σ = 1349506656. Its totient is φ = 1293277120.

The previous prime is 1321391867. The next prime is 1321391893. The reversal of 1321391887 is 7881931231.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1321391887 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1321391867) 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 3 ways as a sum of consecutive naturals, for example, 14057314 + ... + 14057407.

It is an arithmetic number, because the mean of its divisors is an integer number (337376664).

Almost surely, 2^1321391887 is an apocalyptic number.

1321391887 is a deficient number, since it is larger than the sum of its proper divisors (28114769).

1321391887 is an equidigital number, since it uses as much as digits as its factorization.

1321391887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28114768.

The product of its digits is 72576, while the sum is 43.

The square root of 1321391887 is about 36350.9544166312. The cubic root of 1321391887 is about 1097.3467422632.

The spelling of 1321391887 in words is "one billion, three hundred twenty-one million, three hundred ninety-one thousand, eight hundred eighty-seven".