64820209 has 2 divisors, whose sum is σ = 64820210. Its totient is φ = 64820208.

The previous prime is 64820177. The next prime is 64820251. The reversal of 64820209 is 90202846.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62726400 + 2093809 = 7920^2 + 1447^2 .

It is a cyclic number.

It is not a de Polignac number, because 64820209 - 2⁵ = 64820177 is a prime.

It is not a weakly prime, because it can be changed into another prime (64820299) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32410104 + 32410105.

It is an arithmetic number, because the mean of its divisors is an integer number (32410105).

Almost surely, 2^64820209 is an apocalyptic number.

It is an amenable number.

64820209 is a deficient number, since it is larger than the sum of its proper divisors (1).

64820209 is an equidigital number, since it uses as much as digits as its factorization.

64820209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 64820209 is about 8051.0998627517. The cubic root of 64820209 is about 401.7015205566.

The spelling of 64820209 in words is "sixty-four million, eight hundred twenty thousand, two hundred nine".