43665613 has 2 divisors, whose sum is σ = 43665614. Its totient is φ = 43665612.

The previous prime is 43665593. The next prime is 43665631. The reversal of 43665613 is 31656634.

Together with next prime (43665631) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 39967684 + 3697929 = 6322^2 + 1923^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-43665613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (43665653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21832806 + 21832807.

It is an arithmetic number, because the mean of its divisors is an integer number (21832807).

Almost surely, 2^43665613 is an apocalyptic number.

It is an amenable number.

43665613 is a deficient number, since it is larger than the sum of its proper divisors (1).

43665613 is an equidigital number, since it uses as much as digits as its factorization.

43665613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38880, while the sum is 34.

The square root of 43665613 is about 6607.9961410400. The cubic root of 43665613 is about 352.1382382527.

It can be divided in two parts, 436 and 65613, that added together give a square (66049 = 257²).

The spelling of 43665613 in words is "forty-three million, six hundred sixty-five thousand, six hundred thirteen".