6516421 has 2 divisors, whose sum is σ = 6516422. Its totient is φ = 6516420.

The previous prime is 6516401. The next prime is 6516431. The reversal of 6516421 is 1246156.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5239521 + 1276900 = 2289^2 + 1130^2 .

It is a cyclic number.

It is not a de Polignac number, because 6516421 - 2⁹ = 6515909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6516401) 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, 3258210 + 3258211.

It is an arithmetic number, because the mean of its divisors is an integer number (3258211).

Almost surely, 2^6516421 is an apocalyptic number.

It is an amenable number.

6516421 is a deficient number, since it is larger than the sum of its proper divisors (1).

6516421 is an equidigital number, since it uses as much as digits as its factorization.

6516421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1440, while the sum is 25.

The square root of 6516421 is about 2552.7281484717. The cubic root of 6516421 is about 186.7825835440.

The spelling of 6516421 in words is "six million, five hundred sixteen thousand, four hundred twenty-one".