64661803509505 has 4 divisors (see below), whose sum is σ = 77594164211412. Its totient is φ = 51729442807600.

The previous prime is 64661803509487. The next prime is 64661803509587. The reversal of 64661803509505 is 50590530816646.

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 20735555284161 + 43926248225344 = 4553631^2 + 6627688^2 .

It is not a de Polignac number, because 64661803509505 - 2¹⁵ = 64661803476737 is a prime.

It is a super-2 number, since 2×64661803509505² (a number of 28 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 64661803509505.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6466180350946 + ... + 6466180350955.

It is an arithmetic number, because the mean of its divisors is an integer number (19398541052853).

Almost surely, 2^{64661803509505} is an apocalyptic number.

It is an amenable number.

64661803509505 is a deficient number, since it is larger than the sum of its proper divisors (12932360701907).

64661803509505 is a wasteful number, since it uses less digits than its factorization.

64661803509505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12932360701906.

The product of its (nonzero) digits is 23328000, while the sum is 58.

The spelling of 64661803509505 in words is "sixty-four trillion, six hundred sixty-one billion, eight hundred three million, five hundred nine thousand, five hundred five".