6623521 has 2 divisors, whose sum is σ = 6623522. Its totient is φ = 6623520.

The previous prime is 6623467. The next prime is 6623531. The reversal of 6623521 is 1253266.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4264225 + 2359296 = 2065^2 + 1536^2 .

It is a cyclic number.

It is not a de Polignac number, because 6623521 - 2⁹ = 6623009 is a prime.

It is not a weakly prime, because it can be changed into another prime (6623531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3311760 + 3311761.

It is an arithmetic number, because the mean of its divisors is an integer number (3311761).

Almost surely, 2^6623521 is an apocalyptic number.

It is an amenable number.

6623521 is a deficient number, since it is larger than the sum of its proper divisors (1).

6623521 is an equidigital number, since it uses as much as digits as its factorization.

6623521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2160, while the sum is 25.

The square root of 6623521 is about 2573.6202128519. The cubic root of 6623521 is about 187.8003104529.

Adding to 6623521 its reverse (1253266), we get a palindrome (7876787).

The spelling of 6623521 in words is "six million, six hundred twenty-three thousand, five hundred twenty-one".