1991785456386 has 80 divisors (see below), whose sum is σ = 5125062080160. Its totient is φ = 571804427520.

The previous prime is 1991785456379. The next prime is 1991785456483. The reversal of 1991785456386 is 6836545871991.

1991785456386 is a `hidden beast` number, since 1 + 9 + 9 + 1 + 7 + 8 + 54 + 563 + 8 + 6 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 29379951 + ... + 29447666.

It is an arithmetic number, because the mean of its divisors is an integer number (64063276002).

Almost surely, 2^{1991785456386} is an apocalyptic number.

1991785456386 is an abundant number, since it is smaller than the sum of its proper divisors (3133276623774).

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

1991785456386 is a wasteful number, since it uses less digits than its factorization.

1991785456386 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58827661 (or 58827652 counting only the distinct ones).

The product of its digits is 391910400, while the sum is 72.

The spelling of 1991785456386 in words is "one trillion, nine hundred ninety-one billion, seven hundred eighty-five million, four hundred fifty-six thousand, three hundred eighty-six".