81998671 has 2 divisors, whose sum is σ = 81998672. Its totient is φ = 81998670.

The previous prime is 81998669. The next prime is 81998743. The reversal of 81998671 is 17689918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81998671 - 2¹ = 81998669 is a prime.

Together with 81998669, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81998621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40999335 + 40999336.

It is an arithmetic number, because the mean of its divisors is an integer number (40999336).

Almost surely, 2^81998671 is an apocalyptic number.

81998671 is a deficient number, since it is larger than the sum of its proper divisors (1).

81998671 is an equidigital number, since it uses as much as digits as its factorization.

81998671 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 49.

The square root of 81998671 is about 9055.3117560910. The cubic root of 81998671 is about 434.4458014845.

The spelling of 81998671 in words is "eighty-one million, nine hundred ninety-eight thousand, six hundred seventy-one".