2156789 has 2 divisors, whose sum is σ = 2156790. Its totient is φ = 2156788.

The previous prime is 2156761. The next prime is 2156801. The reversal of 2156789 is 9876512.

2156789 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., 2102500 + 54289 = 1450^2 + 233^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2156789 is a prime.

It is a Sophie Germain prime.

It is an Ulam number.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2156719) 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, 1078394 + 1078395.

It is an arithmetic number, because the mean of its divisors is an integer number (1078395).

2^2156789 is an apocalyptic number.

It is an amenable number.

2156789 is a deficient number, since it is larger than the sum of its proper divisors (1).

2156789 is an equidigital number, since it uses as much as digits as its factorization.

2156789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 38.

The square root of 2156789 is about 1468.6010349990. The cubic root of 2156789 is about 129.2019951000.

The spelling of 2156789 in words is "two million, one hundred fifty-six thousand, seven hundred eighty-nine".