3991663 has 12 divisors (see below), whose sum is σ = 4423720. Its totient is φ = 3580272.

The previous prime is 3991649. The next prime is 3991667. The reversal of 3991663 is 3661993.

It is not a de Polignac number, because 3991663 - 2¹³ = 3983471 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3991667) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 28648 + ... + 28786.

Almost surely, 2^3991663 is an apocalyptic number.

3991663 is a deficient number, since it is larger than the sum of its proper divisors (432057).

3991663 is a wasteful number, since it uses less digits than its factorization.

3991663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246 (or 199 counting only the distinct ones).

The product of its digits is 26244, while the sum is 37.

The square root of 3991663 is about 1997.9146628422. The cubic root of 3991663 is about 158.6297437996.

The spelling of 3991663 in words is "three million, nine hundred ninety-one thousand, six hundred sixty-three".