108991609 has 2 divisors, whose sum is σ = 108991610. Its totient is φ = 108991608.

The previous prime is 108991601. The next prime is 108991651. The reversal of 108991609 is 906199801.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 95004009 + 13987600 = 9747^2 + 3740^2 .

It is a cyclic number.

It is not a de Polignac number, because 108991609 - 2³ = 108991601 is a prime.

It is not a weakly prime, because it can be changed into another prime (108991601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 54495804 + 54495805.

It is an arithmetic number, because the mean of its divisors is an integer number (54495805).

Almost surely, 2^108991609 is an apocalyptic number.

It is an amenable number.

108991609 is a deficient number, since it is larger than the sum of its proper divisors (1).

108991609 is an equidigital number, since it uses as much as digits as its factorization.

108991609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34992, while the sum is 43.

The square root of 108991609 is about 10439.9046451584. The cubic root of 108991609 is about 477.6733601130.

The spelling of 108991609 in words is "one hundred eight million, nine hundred ninety-one thousand, six hundred nine".