64728721559 has 4 divisors (see below), whose sum is σ = 66478146504. Its totient is φ = 62979296616.

The previous prime is 64728721537. The next prime is 64728721639. The reversal of 64728721559 is 95512782746.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 95512782746 = 2 ⋅47756391373.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64728721559 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64728721529) 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 in 3 ways as a sum of consecutive naturals, for example, 874712417 + ... + 874712490.

It is an arithmetic number, because the mean of its divisors is an integer number (16619536626).

Almost surely, 2^64728721559 is an apocalyptic number.

64728721559 is a deficient number, since it is larger than the sum of its proper divisors (1749424945).

64728721559 is a wasteful number, since it uses less digits than its factorization.

64728721559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1749424944.

The product of its digits is 8467200, while the sum is 56.

The spelling of 64728721559 in words is "sixty-four billion, seven hundred twenty-eight million, seven hundred twenty-one thousand, five hundred fifty-nine".