3991979798 has 4 divisors (see below), whose sum is σ = 5987969700. Its totient is φ = 1995989898.

The previous prime is 3991979767. The next prime is 3991979813. The reversal of 3991979798 is 8979791993.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8979791993 = 1609 ⋅5580977.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 997994948 + ... + 997994951.

It is an arithmetic number, because the mean of its divisors is an integer number (1496992425).

Almost surely, 2^3991979798 is an apocalyptic number.

3991979798 is a deficient number, since it is larger than the sum of its proper divisors (1995989902).

3991979798 is a wasteful number, since it uses less digits than its factorization.

3991979798 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1995989901.

The product of its digits is 69441624, while the sum is 71.

The square root of 3991979798 is about 63182.1161247390. The cubic root of 3991979798 is about 1586.3394023404.

The spelling of 3991979798 in words is "three billion, nine hundred ninety-one million, nine hundred seventy-nine thousand, seven hundred ninety-eight".