1989861 has 8 divisors (see below), whose sum is σ = 2662080. Its totient is φ = 1322112.

The previous prime is 1989847. The next prime is 1989863. The reversal of 1989861 is 1689891.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1989861 - 2¹⁰ = 1988837 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1989863) 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 7 ways as a sum of consecutive naturals, for example, 120 + ... + 1998.

It is an arithmetic number, because the mean of its divisors is an integer number (332760).

2^1989861 is an apocalyptic number.

It is an amenable number.

1989861 is a deficient number, since it is larger than the sum of its proper divisors (672219).

1989861 is a wasteful number, since it uses less digits than its factorization.

1989861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2235.

The product of its digits is 31104, while the sum is 42.

The square root of 1989861 is about 1410.6243298625. The cubic root of 1989861 is about 125.7788385390.

It can be divided in two parts, 1989 and 861, that added together give a triangular number (2850 = T₇₅).

The spelling of 1989861 in words is "one million, nine hundred eighty-nine thousand, eight hundred sixty-one".