1908991 has 6 divisors (see below), whose sum is σ = 2220720. Its totient is φ = 1636236.

The previous prime is 1908989. The next prime is 1908997. The reversal of 1908991 is 1998091.

It is not a de Polignac number, because 1908991 - 2¹ = 1908989 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1908991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1908997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 19431 + ... + 19528.

It is an arithmetic number, because the mean of its divisors is an integer number (370120).

2^1908991 is an apocalyptic number.

1908991 is a deficient number, since it is larger than the sum of its proper divisors (311729).

1908991 is an equidigital number, since it uses as much as digits as its factorization.

1908991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38973 (or 38966 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 37.

The square root of 1908991 is about 1381.6624044968. The cubic root of 1908991 is about 124.0512925157.

The spelling of 1908991 in words is "one million, nine hundred eight thousand, nine hundred ninety-one".