84991 has 2 divisors, whose sum is σ = 84992. Its totient is φ = 84990.

The previous prime is 84979. The next prime is 85009. The reversal of 84991 is 19948.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 84991 - 2¹⁵ = 52223 is a prime.

84991 is a lucky number.

It is a plaindrome in base 8 and base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (84961) 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 as a sum of consecutive naturals, namely, 42495 + 42496.

It is an arithmetic number, because the mean of its divisors is an integer number (42496).

2⁸⁴⁹⁹¹ is an apocalyptic number.

84991 is a deficient number, since it is larger than the sum of its proper divisors (1).

84991 is an equidigital number, since it uses as much as digits as its factorization.

84991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 31.

The square root of 84991 is about 291.5321594610. The cubic root of 84991 is about 43.9667448446.

The spelling of 84991 in words is "eighty-four thousand, nine hundred ninety-one".