78109 has 4 divisors (see below), whose sum is σ = 82240. Its totient is φ = 73980.

The previous prime is 78101. The next prime is 78121. The reversal of 78109 is 90187.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 78109 - 2³ = 78101 is a prime.

It is a super-2 number, since 2×78109² = 12202031762, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

78109 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78101) 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, 2037 + ... + 2074.

It is an arithmetic number, because the mean of its divisors is an integer number (20560).

2⁷⁸¹⁰⁹ is an apocalyptic number.

It is an amenable number.

78109 is a deficient number, since it is larger than the sum of its proper divisors (4131).

78109 is a wasteful number, since it uses less digits than its factorization.

78109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4130.

The product of its (nonzero) digits is 504, while the sum is 25.

The square root of 78109 is about 279.4798740518. The cubic root of 78109 is about 42.7464801087.

The spelling of 78109 in words is "seventy-eight thousand, one hundred nine".