78991305 has 16 divisors (see below), whose sum is σ = 126640320. Its totient is φ = 42043968.

The previous prime is 78991291. The next prime is 78991321. The reversal of 78991305 is 50319987.

It is a happy number.

It is not a de Polignac number, because 78991305 - 2¹⁰ = 78990281 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2811 + ... + 12879.

It is an arithmetic number, because the mean of its divisors is an integer number (7915020).

Almost surely, 2^78991305 is an apocalyptic number.

It is an amenable number.

78991305 is a deficient number, since it is larger than the sum of its proper divisors (47649015).

78991305 is a wasteful number, since it uses less digits than its factorization.

78991305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10600.

The product of its (nonzero) digits is 68040, while the sum is 42.

The square root of 78991305 is about 8887.7052718911. The cubic root of 78991305 is about 429.0682999911.

The spelling of 78991305 in words is "seventy-eight million, nine hundred ninety-one thousand, three hundred five".