78112109 has 4 divisors (see below), whose sum is σ = 80805660. Its totient is φ = 75418560.

The previous prime is 78112091. The next prime is 78112169. The reversal of 78112109 is 90121187.

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 12145225 + 65966884 = 3485^2 + 8122^2 .

It is not a de Polignac number, because 78112109 - 2⁸ = 78111853 is a prime.

It is a super-2 number, since 2×78112109² = 12203003144855762, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 2693521 = 78112109 / (7 + 8 + 1 + 1 + 2 + 1 + 0 + 9).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78112169) 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, 1346732 + ... + 1346789.

It is an arithmetic number, because the mean of its divisors is an integer number (20201415).

Almost surely, 2^78112109 is an apocalyptic number.

It is an amenable number.

78112109 is a deficient number, since it is larger than the sum of its proper divisors (2693551).

78112109 is a wasteful number, since it uses less digits than its factorization.

78112109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2693550.

The product of its (nonzero) digits is 1008, while the sum is 29.

The square root of 78112109 is about 8838.1055096667. The cubic root of 78112109 is about 427.4704725226.

The spelling of 78112109 in words is "seventy-eight million, one hundred twelve thousand, one hundred nine".