1987771 has 4 divisors (see below), whose sum is σ = 2030112. Its totient is φ = 1945432.

The previous prime is 1987709. The next prime is 1987789. The reversal of 1987771 is 1777891.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1987771 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1987471) 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 3 ways as a sum of consecutive naturals, for example, 21100 + ... + 21193.

It is an arithmetic number, because the mean of its divisors is an integer number (507528).

2^1987771 is an apocalyptic number.

1987771 is a deficient number, since it is larger than the sum of its proper divisors (42341).

1987771 is an equidigital number, since it uses as much as digits as its factorization.

1987771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42340.

The product of its digits is 24696, while the sum is 40.

The square root of 1987771 is about 1409.8833285063. The cubic root of 1987771 is about 125.7347869089.

The spelling of 1987771 in words is "one million, nine hundred eighty-seven thousand, seven hundred seventy-one".