66399555 has 16 divisors (see below), whose sum is σ = 107737344. Its totient is φ = 34913760.

The previous prime is 66399523. The next prime is 66399581. The reversal of 66399555 is 55599366.

It is not a de Polignac number, because 66399555 - 2⁵ = 66399523 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30109 + ... + 32238.

It is an arithmetic number, because the mean of its divisors is an integer number (6733584).

Almost surely, 2^66399555 is an apocalyptic number.

66399555 is a deficient number, since it is larger than the sum of its proper divisors (41337789).

66399555 is a wasteful number, since it uses less digits than its factorization.

66399555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62426.

The product of its digits is 1093500, while the sum is 48.

The square root of 66399555 is about 8148.5922097010. The cubic root of 66399555 is about 404.9378657919.

The spelling of 66399555 in words is "sixty-six million, three hundred ninety-nine thousand, five hundred fifty-five".