394401991680 has 264 divisors, whose sum is σ = 1389764797200. Its totient is φ = 103390543872.

The previous prime is 394401991679. The next prime is 394401991741. The reversal of 394401991680 is 86199104493.

It is a happy number.

394401991680 is a `hidden beast` number, since 3 + 9 + 440 + 199 + 1 + 6 + 8 + 0 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2646186 + ... + 2791254.

Almost surely, 2^394401991680 is an apocalyptic number.

394401991680 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 394401991680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (694882398600).

394401991680 is an abundant number, since it is smaller than the sum of its proper divisors (995362805520).

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

394401991680 is a wasteful number, since it uses less digits than its factorization.

394401991680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145159 (or 145138 counting only the distinct ones).

The product of its (nonzero) digits is 1679616, while the sum is 54.

It can be divided in two parts, 39440 and 1991680, that added together give a triangular number (2031120 = T₂₀₁₅).

The spelling of 394401991680 in words is "three hundred ninety-four billion, four hundred one million, nine hundred ninety-one thousand, six hundred eighty".