81998163 has 48 divisors (see below), whose sum is σ = 134106336. Its totient is φ = 49766400.

The previous prime is 81998143. The next prime is 81998177. The reversal of 81998163 is 36189918.

It is a de Polignac number, because none of the positive numbers 2^k-81998163 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81998143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 318931 + ... + 319187.

It is an arithmetic number, because the mean of its divisors is an integer number (2793882).

Almost surely, 2^81998163 is an apocalyptic number.

81998163 is a deficient number, since it is larger than the sum of its proper divisors (52108173).

81998163 is a wasteful number, since it uses less digits than its factorization.

81998163 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 386 (or 374 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 81998163 is about 9055.2837062126. The cubic root of 81998163 is about 434.4449043199. Note that the first 3 decimals are identical.

The spelling of 81998163 in words is "eighty-one million, nine hundred ninety-eight thousand, one hundred sixty-three".