3921661 has 8 divisors (see below), whose sum is σ = 4120704. Its totient is φ = 3725040.

The previous prime is 3921649. The next prime is 3921677. The reversal of 3921661 is 1661293.

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

It is a cyclic number.

It is not a de Polignac number, because 3921661 - 2¹¹ = 3919613 is a prime.

It is a Duffinian number.

3921661 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3921601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3331 + ... + 4351.

It is an arithmetic number, because the mean of its divisors is an integer number (515088).

Almost surely, 2^3921661 is an apocalyptic number.

It is an amenable number.

3921661 is a deficient number, since it is larger than the sum of its proper divisors (199043).

3921661 is a wasteful number, since it uses less digits than its factorization.

3921661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1211.

The product of its digits is 1944, while the sum is 28.

The square root of 3921661 is about 1980.3184087414. The cubic root of 3921661 is about 157.6969703284.

The spelling of 3921661 in words is "three million, nine hundred twenty-one thousand, six hundred sixty-one".