2189981 has 2 divisors, whose sum is σ = 2189982. Its totient is φ = 2189980.

The previous prime is 2189939. The next prime is 2189987. The reversal of 2189981 is 1899812.

2189981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1651225 + 538756 = 1285^2 + 734^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2189981 is a prime.

It is a super-2 number, since 2×2189981² = 9592033560722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2189987) 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 as a sum of consecutive naturals, namely, 1094990 + 1094991.

It is an arithmetic number, because the mean of its divisors is an integer number (1094991).

2^2189981 is an apocalyptic number.

It is an amenable number.

2189981 is a deficient number, since it is larger than the sum of its proper divisors (1).

2189981 is an equidigital number, since it uses as much as digits as its factorization.

2189981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368, while the sum is 38.

The square root of 2189981 is about 1479.8584391759. The cubic root of 2189981 is about 129.8614104914.

The spelling of 2189981 in words is "two million, one hundred eighty-nine thousand, nine hundred eighty-one".