7987861 has 4 divisors (see below), whose sum is σ = 9128992. Its totient is φ = 6846732.

The previous prime is 7987843. The next prime is 7987867. The reversal of 7987861 is 1687897.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1687897 = 97 ⋅17401.

It is a cyclic number.

It is not a de Polignac number, because 7987861 - 2¹⁵ = 7955093 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 (7987867) 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 3 ways as a sum of consecutive naturals, for example, 570555 + ... + 570568.

It is an arithmetic number, because the mean of its divisors is an integer number (2282248).

Almost surely, 2^7987861 is an apocalyptic number.

It is an amenable number.

7987861 is a deficient number, since it is larger than the sum of its proper divisors (1141131).

7987861 is a wasteful number, since it uses less digits than its factorization.

7987861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1141130.

The product of its digits is 169344, while the sum is 46.

The square root of 7987861 is about 2826.2804177930. The cubic root of 7987861 is about 199.8987904584.

The spelling of 7987861 in words is "seven million, nine hundred eighty-seven thousand, eight hundred sixty-one".