2161729 has 2 divisors, whose sum is σ = 2161730. Its totient is φ = 2161728.

The previous prime is 2161699. The next prime is 2161751. The reversal of 2161729 is 9271612.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2096704 + 65025 = 1448^2 + 255^2 .

It is a cyclic number.

It is not a de Polignac number, because 2161729 - 2⁵ = 2161697 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2161697 and 2161706.

It is not a weakly prime, because it can be changed into another prime (2161759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1080864 + 1080865.

It is an arithmetic number, because the mean of its divisors is an integer number (1080865).

2^2161729 is an apocalyptic number.

It is an amenable number.

2161729 is a deficient number, since it is larger than the sum of its proper divisors (1).

2161729 is an equidigital number, since it uses as much as digits as its factorization.

2161729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1512, while the sum is 28.

The square root of 2161729 is about 1470.2819457505. The cubic root of 2161729 is about 129.3005631066.

The spelling of 2161729 in words is "two million, one hundred sixty-one thousand, seven hundred twenty-nine".