1990808191 has 2 divisors, whose sum is σ = 1990808192. Its totient is φ = 1990808190.

The previous prime is 1990808173. The next prime is 1990808227. The reversal of 1990808191 is 1918080991.

It is a weak prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1618080661 and 1660808161.

It is a cyclic number.

It is not a de Polignac number, because 1990808191 - 2⁷ = 1990808063 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1990805191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995404095 + 995404096.

It is an arithmetic number, because the mean of its divisors is an integer number (995404096).

Almost surely, 2^1990808191 is an apocalyptic number.

1990808191 is a deficient number, since it is larger than the sum of its proper divisors (1).

1990808191 is an equidigital number, since it uses as much as digits as its factorization.

1990808191 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 46656, while the sum is 46.

The square root of 1990808191 is about 44618.4736516165. The cubic root of 1990808191 is about 1257.9879264388.

The spelling of 1990808191 in words is "one billion, nine hundred ninety million, eight hundred eight thousand, one hundred ninety-one".