3991389126 has 8 divisors (see below), whose sum is σ = 7982778264. Its totient is φ = 1330463040.

The previous prime is 3991389107. The next prime is 3991389197. The reversal of 3991389126 is 6219831993.

It is a happy number.

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

3991389126 is an admirable number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 332615755 + ... + 332615766.

It is an arithmetic number, because the mean of its divisors is an integer number (997847283).

Almost surely, 2^3991389126 is an apocalyptic number.

3991389126 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

3991389126 is a wasteful number, since it uses less digits than its factorization.

3991389126 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 665231526.

The product of its digits is 629856, while the sum is 51.

The square root of 3991389126 is about 63177.4415911249. The cubic root of 3991389126 is about 1586.2611577489.

The spelling of 3991389126 in words is "three billion, nine hundred ninety-one million, three hundred eighty-nine thousand, one hundred twenty-six".