103991209 has 4 divisors (see below), whose sum is σ = 118847104. Its totient is φ = 89135316.

The previous prime is 103991207. The next prime is 103991219. The reversal of 103991209 is 902199301.

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 103991209 - 2¹ = 103991207 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (103991203) 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, 7427937 + ... + 7427950.

It is an arithmetic number, because the mean of its divisors is an integer number (29711776).

Almost surely, 2^103991209 is an apocalyptic number.

It is an amenable number.

103991209 is a deficient number, since it is larger than the sum of its proper divisors (14855895).

103991209 is an equidigital number, since it uses as much as digits as its factorization.

103991209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14855894.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 103991209 is about 10197.6080038409. The cubic root of 103991209 is about 470.2536867969.

The spelling of 103991209 in words is "one hundred three million, nine hundred ninety-one thousand, two hundred nine".