1987021 has 4 divisors (see below), whose sum is σ = 1990012. Its totient is φ = 1984032.

The previous prime is 1987003. The next prime is 1987031. The reversal of 1987021 is 1207891.

1987021 is a nontrivial binomial coefficient, being equal to C(1994, 2).

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1207891 = 23 ⋅52517.

It can be written as a sum of positive squares in 2 ways, for example, as 1590121 + 396900 = 1261^2 + 630^2 .

It is a 3-Lehmer number, since φ(1987021) divides (1987021-1)³.

It is a cyclic number.

It is not a de Polignac number, because 1987021 - 2⁵ = 1986989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1987031) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1 + ... + 1993.

It is an arithmetic number, because the mean of its divisors is an integer number (497503).

It is a Poulet number, since it divides 2^1987020-1.

2^1987021 is an apocalyptic number.

1987021 is the 1993-rd triangular number and also the 997-th hexagonal number.

1987021 is the 665-th centered nonagonal number.

It is an amenable number.

1987021 is a deficient number, since it is larger than the sum of its proper divisors (2991).

1987021 is an equidigital number, since it uses as much as digits as its factorization.

1987021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2990.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 1987021 is about 1409.6173239571. The cubic root of 1987021 is about 125.7189713794.

It can be divided in two parts, 19870 and 21, that added together give a palindrome (19891).

The spelling of 1987021 in words is "one million, nine hundred eighty-seven thousand, twenty-one".