66145521555 has 24 divisors (see below), whose sum is σ = 116222821728. Its totient is φ = 34794354816.

The previous prime is 66145521553. The next prime is 66145521569. The reversal of 66145521555 is 55512554166.

It is a happy number.

66145521555 is a `hidden beast` number, since 6 + 6 + 1 + 45 + 52 + 1 + 555 = 666.

It is not a de Polignac number, because 66145521555 - 2¹ = 66145521553 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 66145521555.

It is not an unprimeable number, because it can be changed into a prime (66145521551) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10064527 + ... + 10071096.

It is an arithmetic number, because the mean of its divisors is an integer number (4842617572).

Almost surely, 2^66145521555 is an apocalyptic number.

66145521555 is a deficient number, since it is larger than the sum of its proper divisors (50077300173).

66145521555 is a wasteful number, since it uses less digits than its factorization.

66145521555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20135707 (or 20135704 counting only the distinct ones).

The product of its digits is 900000, while the sum is 45.

The spelling of 66145521555 in words is "sixty-six billion, one hundred forty-five million, five hundred twenty-one thousand, five hundred fifty-five".