8401991388 has 72 divisors (see below), whose sum is σ = 23018712192. Its totient is φ = 2378115936.

The previous prime is 8401991329. The next prime is 8401991401. The reversal of 8401991388 is 8831991048.

It is a self number, because there is not a number n which added to its sum of digits gives 8401991388.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3856 + ... + 129687.

It is an arithmetic number, because the mean of its divisors is an integer number (319704336).

Almost surely, 2^8401991388 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 8401991388, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11509356096).

8401991388 is an abundant number, since it is smaller than the sum of its proper divisors (14616720804).

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

8401991388 is a wasteful number, since it uses less digits than its factorization.

8401991388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133671 (or 133662 counting only the distinct ones).

The product of its (nonzero) digits is 497664, while the sum is 51.

The square root of 8401991388 is about 91662.3771675162. The cubic root of 8401991388 is about 2032.9533389934.

The spelling of 8401991388 in words is "eight billion, four hundred one million, nine hundred ninety-one thousand, three hundred eighty-eight".