2159809 has 2 divisors, whose sum is σ = 2159810. Its totient is φ = 2159808.

The previous prime is 2159789. The next prime is 2159819. The reversal of 2159809 is 9089512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1960000 + 199809 = 1400^2 + 447^2 .

It is a cyclic number.

It is not a de Polignac number, because 2159809 - 2⁷ = 2159681 is a prime.

It is not a weakly prime, because it can be changed into another prime (2159819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1079904 + 1079905.

It is an arithmetic number, because the mean of its divisors is an integer number (1079905).

2^2159809 is an apocalyptic number.

It is an amenable number.

2159809 is a deficient number, since it is larger than the sum of its proper divisors (1).

2159809 is an equidigital number, since it uses as much as digits as its factorization.

2159809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6480, while the sum is 34.

The square root of 2159809 is about 1469.6288647138. The cubic root of 2159809 is about 129.2622711320.

The spelling of 2159809 in words is "two million, one hundred fifty-nine thousand, eight hundred nine".