64516021 has 2 divisors, whose sum is σ = 64516022. Its totient is φ = 64516020.

The previous prime is 64516019. The next prime is 64516027. The reversal of 64516021 is 12061546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62583921 + 1932100 = 7911^2 + 1390^2 .

It is a cyclic number.

It is not a de Polignac number, because 64516021 - 2¹ = 64516019 is a prime.

Together with 64516019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64516027) 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, 32258010 + 32258011.

It is an arithmetic number, because the mean of its divisors is an integer number (32258011).

Almost surely, 2^64516021 is an apocalyptic number.

It is an amenable number.

64516021 is a deficient number, since it is larger than the sum of its proper divisors (1).

64516021 is an equidigital number, since it uses as much as digits as its factorization.

64516021 is an odious number, because the sum of its binary digits is odd.

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

The square root of 64516021 is about 8032.1865640683. The cubic root of 64516021 is about 401.0721673254.

Adding to 64516021 its reverse (12061546), we get a palindrome (76577567).

The spelling of 64516021 in words is "sixty-four million, five hundred sixteen thousand, twenty-one".