6404521 has 2 divisors, whose sum is σ = 6404522. Its totient is φ = 6404520.

The previous prime is 6404477. The next prime is 6404527. The reversal of 6404521 is 1254046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5382400 + 1022121 = 2320^2 + 1011^2 .

It is a cyclic number.

It is not a de Polignac number, because 6404521 - 2⁹ = 6404009 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 6404492 and 6404501.

It is not a weakly prime, because it can be changed into another prime (6404527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3202260 + 3202261.

It is an arithmetic number, because the mean of its divisors is an integer number (3202261).

Almost surely, 2^6404521 is an apocalyptic number.

It is an amenable number.

6404521 is a deficient number, since it is larger than the sum of its proper divisors (1).

6404521 is an equidigital number, since it uses as much as digits as its factorization.

6404521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 6404521 is about 2530.7155114710. The cubic root of 6404521 is about 185.7072610192.

Adding to 6404521 its reverse (1254046), we get a palindrome (7658567).

The spelling of 6404521 in words is "six million, four hundred four thousand, five hundred twenty-one".