43218661 has 2 divisors, whose sum is σ = 43218662. Its totient is φ = 43218660.

The previous prime is 43218653. The next prime is 43218677. The reversal of 43218661 is 16681234.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 32558436 + 10660225 = 5706^2 + 3265^2 .

It is a cyclic number.

It is not a de Polignac number, because 43218661 - 2³ = 43218653 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (43218631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21609330 + 21609331.

It is an arithmetic number, because the mean of its divisors is an integer number (21609331).

Almost surely, 2^43218661 is an apocalyptic number.

It is an amenable number.

43218661 is a deficient number, since it is larger than the sum of its proper divisors (1).

43218661 is an equidigital number, since it uses as much as digits as its factorization.

43218661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6912, while the sum is 31.

The square root of 43218661 is about 6574.0901271583. The cubic root of 43218661 is about 350.9326445486.

Adding to 43218661 its reverse (16681234), we get a palindrome (59899895).

The spelling of 43218661 in words is "forty-three million, two hundred eighteen thousand, six hundred sixty-one".