2178989 has 4 divisors (see below), whose sum is σ = 2220156. Its totient is φ = 2137824.

The previous prime is 2178983. The next prime is 2178991. The reversal of 2178989 is 9898712.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1646089 + 532900 = 1283^2 + 730^2 .

It is a cyclic number.

It is not a de Polignac number, because 2178989 - 2⁸ = 2178733 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2178983) 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, 20504 + ... + 20609.

It is an arithmetic number, because the mean of its divisors is an integer number (555039).

2^2178989 is an apocalyptic number.

It is an amenable number.

2178989 is a deficient number, since it is larger than the sum of its proper divisors (41167).

2178989 is an equidigital number, since it uses as much as digits as its factorization.

2178989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41166.

The product of its digits is 72576, while the sum is 44.

The square root of 2178989 is about 1476.1398985191. The cubic root of 2178989 is about 129.6437782360.

The spelling of 2178989 in words is "two million, one hundred seventy-eight thousand, nine hundred eighty-nine".