391991486883840 has 1152 divisors, whose sum is σ = 1419403254796800. Its totient is φ = 103754264739840.

The previous prime is 391991486883811. The next prime is 391991486883859. The reversal of 391991486883840 is 48388684199193.

391991486883840 is a `hidden beast` number, since 3 + 9 + 1 + 9 + 91 + 486 + 8 + 8 + 3 + 8 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (1152).

It is a Harshad number since it is a multiple of its sum of digits (81).

It is a self number, because there is not a number n which added to its sum of digits gives 391991486883840.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 209509078105 + ... + 209509079975.

It is an arithmetic number, because the mean of its divisors is an integer number (1232120880900).

Almost surely, 2^{391991486883840} is an apocalyptic number.

391991486883840 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 391991486883840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (709701627398400).

391991486883840 is an abundant number, since it is smaller than the sum of its proper divisors (1027411767912960).

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

391991486883840 is a wasteful number, since it uses less digits than its factorization.

391991486883840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2495 (or 2463 counting only the distinct ones).

The product of its (nonzero) digits is 2579890176, while the sum is 81.

The spelling of 391991486883840 in words is "three hundred ninety-one trillion, nine hundred ninety-one billion, four hundred eighty-six million, eight hundred eighty-three thousand, eight hundred forty".