78816172009 has 4 divisors (see below), whose sum is σ = 79100707204. Its totient is φ = 78531636816.

The previous prime is 78816171979. The next prime is 78816172031. The reversal of 78816172009 is 90027161887.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4573546384 + 74242625625 = 67628^2 + 272475^2 .

It is a cyclic number.

It is not a de Polignac number, because 78816172009 - 2⁷ = 78816171881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78816172049) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 142267182 + ... + 142267735.

It is an arithmetic number, because the mean of its divisors is an integer number (19775176801).

Almost surely, 2^78816172009 is an apocalyptic number.

It is an amenable number.

78816172009 is a deficient number, since it is larger than the sum of its proper divisors (284535195).

78816172009 is a wasteful number, since it uses less digits than its factorization.

78816172009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 284535194.

The product of its (nonzero) digits is 338688, while the sum is 49.

The spelling of 78816172009 in words is "seventy-eight billion, eight hundred sixteen million, one hundred seventy-two thousand, nine".