43009661 has 2 divisors, whose sum is σ = 43009662. Its totient is φ = 43009660.

The previous prime is 43009649. The next prime is 43009663. The reversal of 43009661 is 16690034.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 38365636 + 4644025 = 6194^2 + 2155^2 .

It is a cyclic number.

It is not a de Polignac number, because 43009661 - 2¹⁸ = 42747517 is a prime.

Together with 43009663, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (43009663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21504830 + 21504831.

It is an arithmetic number, because the mean of its divisors is an integer number (21504831).

Almost surely, 2^43009661 is an apocalyptic number.

It is an amenable number.

43009661 is a deficient number, since it is larger than the sum of its proper divisors (1).

43009661 is an equidigital number, since it uses as much as digits as its factorization.

43009661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 29.

The square root of 43009661 is about 6558.1751272744. The cubic root of 43009661 is about 350.3660415380.

Adding to 43009661 its reverse (16690034), we get a palindrome (59699695).

The spelling of 43009661 in words is "forty-three million, nine thousand, six hundred sixty-one".