43666561 has 2 divisors, whose sum is σ = 43666562. Its totient is φ = 43666560.

The previous prime is 43666487. The next prime is 43666583. The reversal of 43666561 is 16566634.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25553025 + 18113536 = 5055^2 + 4256^2 .

It is a cyclic number.

It is not a de Polignac number, because 43666561 - 2²³ = 35277953 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 43666561.

It is not a weakly prime, because it can be changed into another prime (43666061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21833280 + 21833281.

It is an arithmetic number, because the mean of its divisors is an integer number (21833281).

Almost surely, 2^43666561 is an apocalyptic number.

It is an amenable number.

43666561 is a deficient number, since it is larger than the sum of its proper divisors (1).

43666561 is an equidigital number, since it uses as much as digits as its factorization.

43666561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77760, while the sum is 37.

The square root of 43666561 is about 6608.0678719275. The cubic root of 43666561 is about 352.1407865939.

The spelling of 43666561 in words is "forty-three million, six hundred sixty-six thousand, five hundred sixty-one".