80121991 has 2 divisors, whose sum is σ = 80121992. Its totient is φ = 80121990.

The previous prime is 80121989. The next prime is 80122001. The reversal of 80121991 is 19912108.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 80121991 - 2¹ = 80121989 is a prime.

Together with 80121989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (80121931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40060995 + 40060996.

It is an arithmetic number, because the mean of its divisors is an integer number (40060996).

Almost surely, 2^80121991 is an apocalyptic number.

80121991 is a deficient number, since it is larger than the sum of its proper divisors (1).

80121991 is an equidigital number, since it uses as much as digits as its factorization.

80121991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 31.

The square root of 80121991 is about 8951.0888164513. The cubic root of 80121991 is about 431.1058448099.

The spelling of 80121991 in words is "eighty million, one hundred twenty-one thousand, nine hundred ninety-one".