78905999 has 2 divisors, whose sum is σ = 78906000. Its totient is φ = 78905998.

The previous prime is 78905977. The next prime is 78906007. The reversal of 78905999 is 99950987.

It is a strong prime.

It is an emirp because it is prime and its reverse (99950987) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78905999 - 2¹² = 78901903 is a prime.

It is a super-3 number, since 3×78905999³ (a number of 25 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78905969) 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, 39452999 + 39453000.

It is an arithmetic number, because the mean of its divisors is an integer number (39453000).

Almost surely, 2^78905999 is an apocalyptic number.

78905999 is a deficient number, since it is larger than the sum of its proper divisors (1).

78905999 is an equidigital number, since it uses as much as digits as its factorization.

78905999 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1837080, while the sum is 56.

The square root of 78905999 is about 8882.9048739700. The cubic root of 78905999 is about 428.9137881143.

The spelling of 78905999 in words is "seventy-eight million, nine hundred five thousand, nine hundred ninety-nine".