987391 has 2 divisors, whose sum is σ = 987392. Its totient is φ = 987390.

The previous prime is 987383. The next prime is 987433. The reversal of 987391 is 193789.

It is a weak prime.

It is an emirp because it is prime and its reverse (193789) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 987391 - 2³ = 987383 is a prime.

It is equal to p₇₇₅₉₉ and since 987391 and 77599 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 987391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (987361) 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 as a sum of consecutive naturals, namely, 493695 + 493696.

It is an arithmetic number, because the mean of its divisors is an integer number (493696).

2⁹⁸⁷³⁹¹ is an apocalyptic number.

987391 is a deficient number, since it is larger than the sum of its proper divisors (1).

987391 is an equidigital number, since it uses as much as digits as its factorization.

987391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13608, while the sum is 37.

The square root of 987391 is about 993.6755003521. The cubic root of 987391 is about 99.5779209996.

It can be divided in two parts, 987 and 391, that added together give a triangular number (1378 = T₅₂).

The spelling of 987391 in words is "nine hundred eighty-seven thousand, three hundred ninety-one".