66556667 has 4 divisors (see below), whose sum is σ = 66623640. Its totient is φ = 66489696.

The previous prime is 66556663. The next prime is 66556669. The reversal of 66556667 is 76665566.

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

It is a cyclic number.

It is not a de Polignac number, because 66556667 - 2² = 66556663 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66556663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31973 + ... + 33990.

It is an arithmetic number, because the mean of its divisors is an integer number (16655910).

Almost surely, 2^66556667 is an apocalyptic number.

66556667 is a deficient number, since it is larger than the sum of its proper divisors (66973).

66556667 is a wasteful number, since it uses less digits than its factorization.

66556667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66972.

The product of its digits is 1360800, while the sum is 47.

The square root of 66556667 is about 8158.2269519792. The cubic root of 66556667 is about 405.2569968713.

The spelling of 66556667 in words is "sixty-six million, five hundred fifty-six thousand, six hundred sixty-seven".