1788991 has 2 divisors, whose sum is σ = 1788992. Its totient is φ = 1788990.

The previous prime is 1788973. The next prime is 1789001. The reversal of 1788991 is 1998871.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1788991 - 2⁷ = 1788863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1788901) 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 as a sum of consecutive naturals, namely, 894495 + 894496.

It is an arithmetic number, because the mean of its divisors is an integer number (894496).

2^1788991 is an apocalyptic number.

1788991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1788991 is an equidigital number, since it uses as much as digits as its factorization.

1788991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 43.

The square root of 1788991 is about 1337.5316818678. The cubic root of 1788991 is about 121.3955364411.

The spelling of 1788991 in words is "one million, seven hundred eighty-eight thousand, nine hundred ninety-one".