3971681 has 4 divisors (see below), whose sum is σ = 4539072. Its totient is φ = 3404292.

The previous prime is 3971677. The next prime is 3971687. The reversal of 3971681 is 1861793.

3971681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1861793 = 79 ⋅23567.

It is a cyclic number.

It is not a de Polignac number, because 3971681 - 2² = 3971677 is a prime.

It is a super-2 number, since 2×3971681² = 31548499931522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (3971687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 283685 + ... + 283698.

It is an arithmetic number, because the mean of its divisors is an integer number (1134768).

Almost surely, 2^3971681 is an apocalyptic number.

It is an amenable number.

3971681 is a deficient number, since it is larger than the sum of its proper divisors (567391).

3971681 is an equidigital number, since it uses as much as digits as its factorization.

3971681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 567390.

The product of its digits is 9072, while the sum is 35.

The square root of 3971681 is about 1992.9076747306. The cubic root of 3971681 is about 158.3646042268.

The spelling of 3971681 in words is "three million, nine hundred seventy-one thousand, six hundred eighty-one".