7978987 has 4 divisors (see below), whose sum is σ = 7992040. Its totient is φ = 7965936.

The previous prime is 7978981. The next prime is 7979009. The reversal of 7978987 is 7898797.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7898797 = 37 ⋅213481.

It is a cyclic number.

It is not a de Polignac number, because 7978987 - 2³ = 7978979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7978981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5562 + ... + 6847.

It is an arithmetic number, because the mean of its divisors is an integer number (1998010).

Almost surely, 2^7978987 is an apocalyptic number.

7978987 is a deficient number, since it is larger than the sum of its proper divisors (13053).

7978987 is a wasteful number, since it uses less digits than its factorization.

7978987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13052.

The product of its digits is 1778112, while the sum is 55.

The square root of 7978987 is about 2824.7100736182. The cubic root of 7978987 is about 199.8247381279.

The spelling of 7978987 in words is "seven million, nine hundred seventy-eight thousand, nine hundred eighty-seven".