66666553 has 4 divisors (see below), whose sum is σ = 66686580. Its totient is φ = 66646528.

The previous prime is 66666517. The next prime is 66666557. The reversal of 66666553 is 35566666.

It is a happy number.

66666553 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 35566666 = 2 ⋅17783333.

It can be written as a sum of positive squares in 2 ways, for example, as 28387584 + 38278969 = 5328^2 + 6187^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66666553 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (66666557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3688 + ... + 12121.

It is an arithmetic number, because the mean of its divisors is an integer number (16671645).

Almost surely, 2^66666553 is an apocalyptic number.

It is an amenable number.

66666553 is a deficient number, since it is larger than the sum of its proper divisors (20027).

66666553 is a wasteful number, since it uses less digits than its factorization.

66666553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20026.

The product of its digits is 583200, while the sum is 43.

The square root of 66666553 is about 8164.9588486409. The cubic root of 66666553 is about 405.4799025902.

The spelling of 66666553 in words is "sixty-six million, six hundred sixty-six thousand, five hundred fifty-three".