6642521 has 2 divisors, whose sum is σ = 6642522. Its totient is φ = 6642520.

The previous prime is 6642497. The next prime is 6642523. The reversal of 6642521 is 1252466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5664400 + 978121 = 2380^2 + 989^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6642521 is a prime.

Together with 6642523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (6642523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3321260 + 3321261.

It is an arithmetic number, because the mean of its divisors is an integer number (3321261).

Almost surely, 2^6642521 is an apocalyptic number.

It is an amenable number.

6642521 is a deficient number, since it is larger than the sum of its proper divisors (1).

6642521 is an equidigital number, since it uses as much as digits as its factorization.

6642521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2880, while the sum is 26.

The square root of 6642521 is about 2577.3088677921. The cubic root of 6642521 is about 187.9797114819.

Adding to 6642521 its reverse (1252466), we get a palindrome (7894987).

The spelling of 6642521 in words is "six million, six hundred forty-two thousand, five hundred twenty-one".