78145051991 has 2 divisors, whose sum is σ = 78145051992. Its totient is φ = 78145051990.

The previous prime is 78145051909. The next prime is 78145051993. The reversal of 78145051991 is 19915054187.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78145051991 - 2¹⁸ = 78144789847 is a prime.

It is a super-2 number, since 2×78145051991² (a number of 23 digits) contains 22 as substring.

Together with 78145051993, 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 (78145051993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39072525995 + 39072525996.

It is an arithmetic number, because the mean of its divisors is an integer number (39072525996).

Almost surely, 2^78145051991 is an apocalyptic number.

78145051991 is a deficient number, since it is larger than the sum of its proper divisors (1).

78145051991 is an equidigital number, since it uses as much as digits as its factorization.

78145051991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 453600, while the sum is 50.

The spelling of 78145051991 in words is "seventy-eight billion, one hundred forty-five million, fifty-one thousand, nine hundred ninety-one".