111978109 has 4 divisors (see below), whose sum is σ = 113236380. Its totient is φ = 110719840.

The previous prime is 111978103. The next prime is 111978121. The reversal of 111978109 is 901879111.

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 31606884 + 80371225 = 5622^2 + 8965^2 .

It is a cyclic number.

It is not a de Polignac number, because 111978109 - 2⁷ = 111977981 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (111978103) 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, 629002 + ... + 629179.

It is an arithmetic number, because the mean of its divisors is an integer number (28309095).

Almost surely, 2^111978109 is an apocalyptic number.

It is an amenable number.

111978109 is a deficient number, since it is larger than the sum of its proper divisors (1258271).

111978109 is an equidigital number, since it uses as much as digits as its factorization.

111978109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1258270.

The product of its (nonzero) digits is 4536, while the sum is 37.

The square root of 111978109 is about 10581.9709411810. The cubic root of 111978109 is about 481.9970457743.

It can be divided in two parts, 11197 and 8109, that added together give a triangular number (19306 = T₁₉₆).

The spelling of 111978109 in words is "one hundred eleven million, nine hundred seventy-eight thousand, one hundred nine".