66514553521 has 4 divisors (see below), whose sum is σ = 71631057652. Its totient is φ = 61398049392.

The previous prime is 66514553509. The next prime is 66514553531. The reversal of 66514553521 is 12535541566.

It is a happy number.

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 45768184225 + 20746369296 = 213935^2 + 144036^2 .

It is a cyclic number.

It is not a de Polignac number, because 66514553521 - 2⁵ = 66514553489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66514553531) 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, 2558252046 + ... + 2558252071.

It is an arithmetic number, because the mean of its divisors is an integer number (17907764413).

Almost surely, 2^66514553521 is an apocalyptic number.

It is an amenable number.

66514553521 is a deficient number, since it is larger than the sum of its proper divisors (5116504131).

66514553521 is a wasteful number, since it uses less digits than its factorization.

66514553521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5116504130.

The product of its digits is 540000, while the sum is 43.

The spelling of 66514553521 in words is "sixty-six billion, five hundred fourteen million, five hundred fifty-three thousand, five hundred twenty-one".