81920191563 has 32 divisors (see below), whose sum is σ = 138783321600. Its totient is φ = 46783705248.

The previous prime is 81920191541. The next prime is 81920191567. The reversal of 81920191563 is 36519102918.

81920191563 is a `hidden beast` number, since 81 + 9 + 2 + 0 + 1 + 9 + 1 + 563 = 666.

It is not a de Polignac number, because 81920191563 - 2¹⁷ = 81920060491 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81920191567) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 191968 + ... + 447986.

It is an arithmetic number, because the mean of its divisors is an integer number (4336978800).

Almost surely, 2^81920191563 is an apocalyptic number.

81920191563 is a deficient number, since it is larger than the sum of its proper divisors (56863130037).

81920191563 is a wasteful number, since it uses less digits than its factorization.

81920191563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 257728 (or 257722 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 45.

The spelling of 81920191563 in words is "eighty-one billion, nine hundred twenty million, one hundred ninety-one thousand, five hundred sixty-three".