75991 has 2 divisors, whose sum is σ = 75992. Its totient is φ = 75990.

The previous prime is 75989. The next prime is 75997. The reversal of 75991 is 19957.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 75991 - 2¹ = 75989 is a prime.

Together with 75989, it forms a pair of twin primes.

It is a d-powerful number, because it can be written as 7⁵ + 5³ + 9 + 9⁵ + 1 .

75991 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (75997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 37995 + 37996.

It is an arithmetic number, because the mean of its divisors is an integer number (37996).

2⁷⁵⁹⁹¹ is an apocalyptic number.

75991 is a deficient number, since it is larger than the sum of its proper divisors (1).

75991 is an equidigital number, since it uses as much as digits as its factorization.

75991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2835, while the sum is 31.

The square root of 75991 is about 275.6646513429. The cubic root of 75991 is about 42.3565637409.

The spelling of 75991 in words is "seventy-five thousand, nine hundred ninety-one".