3996721 has 8 divisors (see below), whose sum is σ = 4191264. Its totient is φ = 3806880.

The previous prime is 3996653. The next prime is 3996743. The reversal of 3996721 is 1276993.

3996721 = 179² + 180² + ... + 260².

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 3996721 - 2¹⁹ = 3472433 is a prime.

It is a Duffinian number.

3996721 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (3996791) 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, 630 + ... + 2896.

It is an arithmetic number, because the mean of its divisors is an integer number (523908).

Almost surely, 2^3996721 is an apocalyptic number.

It is an amenable number.

3996721 is a deficient number, since it is larger than the sum of its proper divisors (194543).

3996721 is a wasteful number, since it uses less digits than its factorization.

3996721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2351.

The product of its digits is 20412, while the sum is 37.

The square root of 3996721 is about 1999.1800819336. The cubic root of 3996721 is about 158.6967176053.

The spelling of 3996721 in words is "three million, nine hundred ninety-six thousand, seven hundred twenty-one".