1608109991 has 2 divisors, whose sum is σ = 1608109992. Its totient is φ = 1608109990.

The previous prime is 1608109961. The next prime is 1608110033. The reversal of 1608109991 is 1999018061.

It is a weak prime.

It is an emirp because it is prime and its reverse (1999018061) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1666018091 and 1908106661.

It is a cyclic number.

It is not a de Polignac number, because 1608109991 - 2¹⁰ = 1608108967 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1608109931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 804054995 + 804054996.

It is an arithmetic number, because the mean of its divisors is an integer number (804054996).

Almost surely, 2^1608109991 is an apocalyptic number.

1608109991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1608109991 is an equidigital number, since it uses as much as digits as its factorization.

1608109991 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 44.

The square root of 1608109991 is about 40101.2467511922. The cubic root of 1608109991 is about 1171.5799122569.

The spelling of 1608109991 in words is "one billion, six hundred eight million, one hundred nine thousand, nine hundred ninety-one".