3991828621 has 16 divisors (see below), whose sum is σ = 4398338880. Its totient is φ = 3592664320.

The previous prime is 3991828619. The next prime is 3991828651. The reversal of 3991828621 is 1268281993.

It is a cyclic number.

It is not a de Polignac number, because 3991828621 - 2¹ = 3991828619 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 (3991828651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1705470 + ... + 1707808.

It is an arithmetic number, because the mean of its divisors is an integer number (274896180).

Almost surely, 2^3991828621 is an apocalyptic number.

It is an amenable number.

3991828621 is a deficient number, since it is larger than the sum of its proper divisors (406510259).

3991828621 is a wasteful number, since it uses less digits than its factorization.

3991828621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3836.

The product of its digits is 373248, while the sum is 49.

The square root of 3991828621 is about 63180.9197543056. The cubic root of 3991828621 is about 1586.3193771005.

The spelling of 3991828621 in words is "three billion, nine hundred ninety-one million, eight hundred twenty-eight thousand, six hundred twenty-one".