3971639 has 4 divisors (see below), whose sum is σ = 4539024. Its totient is φ = 3404256.

The previous prime is 3971621. The next prime is 3971651. The reversal of 3971639 is 9361793.

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 3971639 - 2¹⁶ = 3906103 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3971239) 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, 283682 + ... + 283695.

It is an arithmetic number, because the mean of its divisors is an integer number (1134756).

Almost surely, 2^3971639 is an apocalyptic number.

3971639 is a deficient number, since it is larger than the sum of its proper divisors (567385).

3971639 is an equidigital number, since it uses as much as digits as its factorization.

3971639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 567384.

The product of its digits is 30618, while the sum is 38.

The square root of 3971639 is about 1992.8971373355. The cubic root of 3971639 is about 158.3640459966.

The spelling of 3971639 in words is "three million, nine hundred seventy-one thousand, six hundred thirty-nine".