1811987 has 2 divisors, whose sum is σ = 1811988. Its totient is φ = 1811986.

The previous prime is 1811983. The next prime is 1811993. The reversal of 1811987 is 7891181.

It is a weak prime.

It is an emirp because it is prime and its reverse (7891181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1811987 - 2² = 1811983 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1811983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 905993 + 905994.

It is an arithmetic number, because the mean of its divisors is an integer number (905994).

2^1811987 is an apocalyptic number.

1811987 is a deficient number, since it is larger than the sum of its proper divisors (1).

1811987 is an equidigital number, since it uses as much as digits as its factorization.

1811987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4032, while the sum is 35.

The square root of 1811987 is about 1346.1006648836. The cubic root of 1811987 is about 121.9134699508.

The spelling of 1811987 in words is "one million, eight hundred eleven thousand, nine hundred eighty-seven".