66556505 has 4 divisors (see below), whose sum is σ = 79867812. Its totient is φ = 53245200.

The previous prime is 66556493. The next prime is 66556507. The reversal of 66556505 is 50565566.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10426441 + 56130064 = 3229^2 + 7492^2 .

It is not a de Polignac number, because 66556505 - 2¹⁶ = 66490969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66556507) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6655646 + ... + 6655655.

It is an arithmetic number, because the mean of its divisors is an integer number (19966953).

Almost surely, 2^66556505 is an apocalyptic number.

It is an amenable number.

66556505 is a deficient number, since it is larger than the sum of its proper divisors (13311307).

66556505 is a wasteful number, since it uses less digits than its factorization.

66556505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13311306.

The product of its (nonzero) digits is 135000, while the sum is 38.

The square root of 66556505 is about 8158.2170233452. The cubic root of 66556505 is about 405.2566680703.

The spelling of 66556505 in words is "sixty-six million, five hundred fifty-six thousand, five hundred five".