64421809 has 2 divisors, whose sum is σ = 64421810. Its totient is φ = 64421808.

The previous prime is 64421807. The next prime is 64421879. The reversal of 64421809 is 90812446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 37173409 + 27248400 = 6097^2 + 5220^2 .

It is a cyclic number.

It is not a de Polignac number, because 64421809 - 2¹ = 64421807 is a prime.

Together with 64421807, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (64421803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32210904 + 32210905.

It is an arithmetic number, because the mean of its divisors is an integer number (32210905).

Almost surely, 2^64421809 is an apocalyptic number.

It is an amenable number.

64421809 is a deficient number, since it is larger than the sum of its proper divisors (1).

64421809 is an equidigital number, since it uses as much as digits as its factorization.

64421809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13824, while the sum is 34.

The square root of 64421809 is about 8026.3197668670. The cubic root of 64421809 is about 400.8768452017.

The spelling of 64421809 in words is "sixty-four million, four hundred twenty-one thousand, eight hundred nine".