2189991 has 16 divisors (see below), whose sum is σ = 3227904. Its totient is φ = 1313664.

The previous prime is 2189989. The next prime is 2190017. The reversal of 2189991 is 1999812.

It is a happy number.

2189991 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 2189991 - 2¹ = 2189989 is a prime.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2189981) 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 15 ways as a sum of consecutive naturals, for example, 240 + ... + 2106.

It is an arithmetic number, because the mean of its divisors is an integer number (201744).

2^2189991 is an apocalyptic number.

2189991 is a deficient number, since it is larger than the sum of its proper divisors (1037913).

2189991 is a wasteful number, since it uses less digits than its factorization.

2189991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1910.

The product of its digits is 11664, while the sum is 39.

The square root of 2189991 is about 1479.8618178735. The cubic root of 2189991 is about 129.8616081509.

The spelling of 2189991 in words is "two million, one hundred eighty-nine thousand, nine hundred ninety-one".