3991394534400 has 4224 divisors, whose sum is σ = 19649942323200. Its totient is φ = 770782003200.

The previous prime is 3991394534389. The next prime is 3991394534411. The reversal of 3991394534400 is 44354931993.

3991394534400 is a `hidden beast` number, since 3 + 9 + 9 + 13 + 94 + 534 + 4 + 0 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (3991394534389) and next prime (3991394534411).

It is a harmonic number, since the harmonic mean of its divisors is an integer.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 44847129556 + ... + 44847129644.

Almost surely, 2^{3991394534400} is an apocalyptic number.

3991394534400 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 3991394534400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9824971161600).

3991394534400 is an abundant number, since it is smaller than the sum of its proper divisors (15658547788800).

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

3991394534400 is a wasteful number, since it uses less digits than its factorization.

3991394534400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202 (or 173 counting only the distinct ones).

The product of its (nonzero) digits is 6298560, while the sum is 54.

The spelling of 3991394534400 in words is "three trillion, nine hundred ninety-one billion, three hundred ninety-four million, five hundred thirty-four thousand, four hundred".