2168521 has 2 divisors, whose sum is σ = 2168522. Its totient is φ = 2168520.

The previous prime is 2168519. The next prime is 2168549. The reversal of 2168521 is 1258612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1860496 + 308025 = 1364^2 + 555^2 .

It is a cyclic number.

It is not a de Polignac number, because 2168521 - 2¹ = 2168519 is a prime.

Together with 2168519, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (2168501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1084260 + 1084261.

It is an arithmetic number, because the mean of its divisors is an integer number (1084261).

2^2168521 is an apocalyptic number.

It is an amenable number.

2168521 is a deficient number, since it is larger than the sum of its proper divisors (1).

2168521 is an equidigital number, since it uses as much as digits as its factorization.

2168521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 960, while the sum is 25.

The square root of 2168521 is about 1472.5898953884. The cubic root of 2168521 is about 129.4358392782.

Subtracting from 2168521 its reverse (1258612), we obtain a palindrome (909909).

The spelling of 2168521 in words is "two million, one hundred sixty-eight thousand, five hundred twenty-one".