64821209 has 2 divisors, whose sum is σ = 64821210. Its totient is φ = 64821208.

The previous prime is 64821193. The next prime is 64821233. The reversal of 64821209 is 90212846.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 37027225 + 27793984 = 6085^2 + 5272^2 .

It is a cyclic number.

It is not a de Polignac number, because 64821209 - 2⁴ = 64821193 is a prime.

It is not a weakly prime, because it can be changed into another prime (64820209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32410604 + 32410605.

It is an arithmetic number, because the mean of its divisors is an integer number (32410605).

Almost surely, 2^64821209 is an apocalyptic number.

It is an amenable number.

64821209 is a deficient number, since it is larger than the sum of its proper divisors (1).

64821209 is an equidigital number, since it uses as much as digits as its factorization.

64821209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 64821209 is about 8051.1619658283. The cubic root of 64821209 is about 401.7035862676.

The spelling of 64821209 in words is "sixty-four million, eight hundred twenty-one thousand, two hundred nine".