66521705601 has 32 divisors (see below), whose sum is σ = 99988439040. Its totient is φ = 39057883200.

The previous prime is 66521705599. The next prime is 66521705611. The reversal of 66521705601 is 10650712566.

It is not a de Polignac number, because 66521705601 - 2¹ = 66521705599 is a prime.

It is a super-2 number, since 2×66521705601² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 66521705601.

It is not an unprimeable number, because it can be changed into a prime (66521705611) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 301641 + ... + 473318.

It is an arithmetic number, because the mean of its divisors is an integer number (3124638720).

Almost surely, 2^66521705601 is an apocalyptic number.

It is an amenable number.

66521705601 is a deficient number, since it is larger than the sum of its proper divisors (33466733439).

66521705601 is a wasteful number, since it uses less digits than its factorization.

66521705601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 775077.

The product of its (nonzero) digits is 75600, while the sum is 39.

The spelling of 66521705601 in words is "sixty-six billion, five hundred twenty-one million, seven hundred five thousand, six hundred one".