66567661 has 4 divisors (see below), whose sum is σ = 66663324. Its totient is φ = 66472000.

The previous prime is 66567647. The next prime is 66567701. The reversal of 66567661 is 16676566.

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 59444100 + 7123561 = 7710^2 + 2669^2 .

It is a cyclic number.

It is not a de Polignac number, because 66567661 - 2¹⁷ = 66436589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66565661) 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, 46780 + ... + 48181.

It is an arithmetic number, because the mean of its divisors is an integer number (16665831).

Almost surely, 2^66567661 is an apocalyptic number.

It is an amenable number.

66567661 is a deficient number, since it is larger than the sum of its proper divisors (95663).

66567661 is an equidigital number, since it uses as much as digits as its factorization.

66567661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95662.

The product of its digits is 272160, while the sum is 43.

The square root of 66567661 is about 8158.9007225238. The cubic root of 66567661 is about 405.2793094376.

The spelling of 66567661 in words is "sixty-six million, five hundred sixty-seven thousand, six hundred sixty-one".