1987221 has 4 divisors (see below), whose sum is σ = 2649632. Its totient is φ = 1324812.

The previous prime is 1987217. The next prime is 1987231. The reversal of 1987221 is 1227891.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1987221 - 2² = 1987217 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1987201) 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 in 3 ways as a sum of consecutive naturals, for example, 331201 + ... + 331206.

It is an arithmetic number, because the mean of its divisors is an integer number (662408).

2^1987221 is an apocalyptic number.

It is an amenable number.

1987221 is a deficient number, since it is larger than the sum of its proper divisors (662411).

1987221 is an equidigital number, since it uses as much as digits as its factorization.

1987221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 662410.

The product of its digits is 2016, while the sum is 30.

The square root of 1987221 is about 1409.6882634115. The cubic root of 1987221 is about 125.7231892430.

The spelling of 1987221 in words is "one million, nine hundred eighty-seven thousand, two hundred twenty-one".