64808921 has 2 divisors, whose sum is σ = 64808922. Its totient is φ = 64808920.

The previous prime is 64808839. The next prime is 64808923. The reversal of 64808921 is 12980846.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 37393225 + 27415696 = 6115^2 + 5236^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64808921 is a prime.

Together with 64808923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (64808923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32404460 + 32404461.

It is an arithmetic number, because the mean of its divisors is an integer number (32404461).

Almost surely, 2^64808921 is an apocalyptic number.

It is an amenable number.

64808921 is a deficient number, since it is larger than the sum of its proper divisors (1).

64808921 is an equidigital number, since it uses as much as digits as its factorization.

64808921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 64808921 is about 8050.3988099969. The cubic root of 64808921 is about 401.6782013373.

The spelling of 64808921 in words is "sixty-four million, eight hundred eight thousand, nine hundred twenty-one".