64768517356321 has 3 divisors (see below), whose sum is σ = 64768525404211. Its totient is φ = 64768509308432.

The previous prime is 64768517356229. The next prime is 64768517356349. The reversal of 64768517356321 is 12365371586746.

The square root of 64768517356321 is 8047889.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 41548840413921 + 23219676942400 = 6445839^2 + 4818680^2 .

It is a de Polignac number, because none of the positive numbers 2^k-64768517356321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64768517356391) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4023945 + ... + 12071833.

Almost surely, 2^{64768517356321} is an apocalyptic number.

64768517356321 is the 8047889-th square number.

64768517356321 is the 4023945-th centered octagonal number.

It is an amenable number.

64768517356321 is a deficient number, since it is larger than the sum of its proper divisors (8047890).

64768517356321 is an frugal number, since it uses more digits than its factorization.

64768517356321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16095778 (or 8047889 counting only the distinct ones).

The product of its digits is 152409600, while the sum is 64.

The spelling of 64768517356321 in words is "sixty-four trillion, seven hundred sixty-eight billion, five hundred seventeen million, three hundred fifty-six thousand, three hundred twenty-one".