66521137706465 has 8 divisors (see below), whose sum is σ = 85965777959208. Its totient is φ = 49123301690880.

The previous prime is 66521137706459. The next prime is 66521137706467. The reversal of 66521137706465 is 56460773112566.

It can be written as a sum of positive squares in 4 ways, for example, as 2634895111696 + 63886242594769 = 1623236^2 + 7992887^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66521137706465 - 2³⁴ = 66503957837281 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66521137706467) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 511701059216 + ... + 511701059345.

It is an arithmetic number, because the mean of its divisors is an integer number (10745722244901).

Almost surely, 2^{66521137706465} is an apocalyptic number.

66521137706465 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66521137706465 is a deficient number, since it is larger than the sum of its proper divisors (19444640252743).

66521137706465 is a wasteful number, since it uses less digits than its factorization.

66521137706465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1023402118579.

The product of its (nonzero) digits is 38102400, while the sum is 59.

The spelling of 66521137706465 in words is "sixty-six trillion, five hundred twenty-one billion, one hundred thirty-seven million, seven hundred six thousand, four hundred sixty-five".