66520555 has 4 divisors (see below), whose sum is σ = 79824672. Its totient is φ = 53216440.

The previous prime is 66520547. The next prime is 66520583. The reversal of 66520555 is 55502566.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 66520555 - 2³ = 66520547 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66520555.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 6652051 + ... + 6652060.

It is an arithmetic number, because the mean of its divisors is an integer number (19956168).

Almost surely, 2^66520555 is an apocalyptic number.

66520555 is a deficient number, since it is larger than the sum of its proper divisors (13304117).

66520555 is a wasteful number, since it uses less digits than its factorization.

66520555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13304116.

The product of its (nonzero) digits is 45000, while the sum is 34.

The square root of 66520555 is about 8156.0134256878. The cubic root of 66520555 is about 405.1836894731.

The spelling of 66520555 in words is "sixty-six million, five hundred twenty thousand, five hundred fifty-five".