78379991 has 2 divisors, whose sum is σ = 78379992. Its totient is φ = 78379990.

The previous prime is 78379957. The next prime is 78379993. The reversal of 78379991 is 19997387.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78379991 is a prime.

It is a super-2 number, since 2×78379991² = 12286845978320162, which contains 22 as substring.

Together with 78379993, 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 (78379993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39189995 + 39189996.

It is an arithmetic number, because the mean of its divisors is an integer number (39189996).

Almost surely, 2^78379991 is an apocalyptic number.

78379991 is a deficient number, since it is larger than the sum of its proper divisors (1).

78379991 is an equidigital number, since it uses as much as digits as its factorization.

78379991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 857304, while the sum is 53.

The square root of 78379991 is about 8853.2474832685. The cubic root of 78379991 is about 427.9585786187.

The spelling of 78379991 in words is "seventy-eight million, three hundred seventy-nine thousand, nine hundred ninety-one".