2189781 has 32 divisors (see below), whose sum is σ = 3623040. Its totient is φ = 1296000.

The previous prime is 2189767. The next prime is 2189783. The reversal of 2189781 is 1879812.

2189781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 2189781 - 2¹⁰ = 2188757 is a prime.

It is a super-2 number, since 2×2189781² = 9590281655922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2189783) 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 31 ways as a sum of consecutive naturals, for example, 21631 + ... + 21731.

It is an arithmetic number, because the mean of its divisors is an integer number (113220).

2^2189781 is an apocalyptic number.

It is an amenable number.

2189781 is a deficient number, since it is larger than the sum of its proper divisors (1433259).

2189781 is a wasteful number, since it uses less digits than its factorization.

2189781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194 (or 188 counting only the distinct ones).

The product of its digits is 8064, while the sum is 36.

The square root of 2189781 is about 1479.7908636020. The cubic root of 2189781 is about 129.8574571735.

It can be divided in two parts, 218 and 9781, that added together give a palindrome (9999).

The spelling of 2189781 in words is "two million, one hundred eighty-nine thousand, seven hundred eighty-one".