66555555 has 32 divisors (see below), whose sum is σ = 116633088. Its totient is φ = 32140800.

The previous prime is 66555553. The next prime is 66555581. The reversal of 66555555 is 55555566.

It is not a de Polignac number, because 66555555 - 2¹ = 66555553 is a prime.

66555555 is a modest number, since divided by 55555 gives 665 as remainder.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (66555553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 50667 + ... + 51963.

It is an arithmetic number, because the mean of its divisors is an integer number (3644784).

Almost surely, 2^66555555 is an apocalyptic number.

66555555 is a deficient number, since it is larger than the sum of its proper divisors (50077533).

66555555 is a wasteful number, since it uses less digits than its factorization.

66555555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1627.

The product of its digits is 562500, while the sum is 42.

The square root of 66555555 is about 8158.1587996312. The cubic root of 66555555 is about 405.2547399059.

The spelling of 66555555 in words is "sixty-six million, five hundred fifty-five thousand, five hundred fifty-five".