1990987 has 2 divisors, whose sum is σ = 1990988. Its totient is φ = 1990986.

The previous prime is 1990981. The next prime is 1991027. The reversal of 1990987 is 7890991.

It is a weak prime.

It is an emirp because it is prime and its reverse (7890991) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1990987 is a prime.

It is not a weakly prime, because it can be changed into another prime (1990981) 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, 995493 + 995494.

It is an arithmetic number, because the mean of its divisors is an integer number (995494).

2^1990987 is an apocalyptic number.

1990987 is a deficient number, since it is larger than the sum of its proper divisors (1).

1990987 is an equidigital number, since it uses as much as digits as its factorization.

1990987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40824, while the sum is 43.

The square root of 1990987 is about 1411.0233874745. The cubic root of 1990987 is about 125.8025588334.

The spelling of 1990987 in words is "one million, nine hundred ninety thousand, nine hundred eighty-seven".