3921681 has 8 divisors (see below), whose sum is σ = 5242720. Its totient is φ = 2607552.

The previous prime is 3921677. The next prime is 3921683. The reversal of 3921681 is 1861293.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 3921681 - 2² = 3921677 is a prime.

It is a super-2 number, since 2×3921681² = 30759163731522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3921683) 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 7 ways as a sum of consecutive naturals, for example, 211 + ... + 2808.

It is an arithmetic number, because the mean of its divisors is an integer number (655340).

Almost surely, 2^3921681 is an apocalyptic number.

It is an amenable number.

3921681 is a deficient number, since it is larger than the sum of its proper divisors (1321039).

3921681 is a wasteful number, since it uses less digits than its factorization.

3921681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3455.

The product of its digits is 2592, while the sum is 30.

The square root of 3921681 is about 1980.3234584279. The cubic root of 3921681 is about 157.6972384065.

The spelling of 3921681 in words is "three million, nine hundred twenty-one thousand, six hundred eighty-one".