3971985887 has 4 divisors (see below), whose sum is σ = 4100114496. Its totient is φ = 3843857280.

The previous prime is 3971985883. The next prime is 3971985889. The reversal of 3971985887 is 7885891793.

It is a happy number.

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 3971985887 - 2² = 3971985883 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 (3971985881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64064258 + ... + 64064319.

It is an arithmetic number, because the mean of its divisors is an integer number (1025028624).

Almost surely, 2^3971985887 is an apocalyptic number.

3971985887 is a deficient number, since it is larger than the sum of its proper divisors (128128609).

3971985887 is a wasteful number, since it uses less digits than its factorization.

3971985887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128128608.

The product of its digits is 30481920, while the sum is 65.

The square root of 3971985887 is about 63023.6930606260. The cubic root of 3971985887 is about 1583.6865642144.

The spelling of 3971985887 in words is "three billion, nine hundred seventy-one million, nine hundred eighty-five thousand, eight hundred eighty-seven".