3971987 has 4 divisors (see below), whose sum is σ = 4079376. Its totient is φ = 3864600.

The previous prime is 3971983. The next prime is 3971993. The reversal of 3971987 is 7891793.

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

It is a cyclic number.

It is not a de Polignac number, because 3971987 - 2² = 3971983 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3971983) 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, 53639 + ... + 53712.

It is an arithmetic number, because the mean of its divisors is an integer number (1019844).

Almost surely, 2^3971987 is an apocalyptic number.

3971987 is a gapful number since it is divisible by the number (37) formed by its first and last digit.

3971987 is a deficient number, since it is larger than the sum of its proper divisors (107389).

3971987 is a wasteful number, since it uses less digits than its factorization.

3971987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107388.

The product of its digits is 95256, while the sum is 44.

The square root of 3971987 is about 1992.9844454988. The cubic root of 3971987 is about 158.3686712137.

The spelling of 3971987 in words is "three million, nine hundred seventy-one thousand, nine hundred eighty-seven".