7971987 has 4 divisors (see below), whose sum is σ = 10629320. Its totient is φ = 5314656.

The previous prime is 7971973. The next prime is 7972009. The reversal of 7971987 is 7891797.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7891797 = 3 ⋅2630599.

It is not a de Polignac number, because 7971987 - 2¹⁴ = 7955603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7971787) 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, 1328662 + ... + 1328667.

It is an arithmetic number, because the mean of its divisors is an integer number (2657330).

Almost surely, 2^7971987 is an apocalyptic number.

7971987 is a deficient number, since it is larger than the sum of its proper divisors (2657333).

7971987 is a wasteful number, since it uses less digits than its factorization.

7971987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2657332.

The product of its digits is 222264, while the sum is 48.

The square root of 7971987 is about 2823.4707365227. The cubic root of 7971987 is about 199.7662853270.

The spelling of 7971987 in words is "seven million, nine hundred seventy-one thousand, nine hundred eighty-seven".