64640689695361 has 4 divisors (see below), whose sum is σ = 69613050441172. Its totient is φ = 59668328949552.

The previous prime is 64640689695289. The next prime is 64640689695409. The reversal of 64640689695361 is 16359698604646.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14225577565761 + 50415112129600 = 3771681^2 + 7100360^2 .

It is a cyclic number.

It is not a de Polignac number, because 64640689695361 - 2¹⁷ = 64640689564289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64640689695061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2486180372886 + ... + 2486180372911.

It is an arithmetic number, because the mean of its divisors is an integer number (17403262610293).

Almost surely, 2^{64640689695361} is an apocalyptic number.

It is an amenable number.

64640689695361 is a deficient number, since it is larger than the sum of its proper divisors (4972360745811).

64640689695361 is a wasteful number, since it uses less digits than its factorization.

64640689695361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4972360745810.

The product of its (nonzero) digits is 1209323520, while the sum is 73.

The spelling of 64640689695361 in words is "sixty-four trillion, six hundred forty billion, six hundred eighty-nine million, six hundred ninety-five thousand, three hundred sixty-one".