1943398661 has 2 divisors, whose sum is σ = 1943398662. Its totient is φ = 1943398660.

The previous prime is 1943398643. The next prime is 1943398697. The reversal of 1943398661 is 1668933491.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1941724225 + 1674436 = 44065^2 + 1294^2 .

It is a cyclic number.

It is not a de Polignac number, because 1943398661 - 2¹⁴ = 1943382277 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1943398861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 971699330 + 971699331.

It is an arithmetic number, because the mean of its divisors is an integer number (971699331).

Almost surely, 2^1943398661 is an apocalyptic number.

It is an amenable number.

1943398661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1943398661 is an equidigital number, since it uses as much as digits as its factorization.

1943398661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 839808, while the sum is 50.

The square root of 1943398661 is about 44083.9955199163. The cubic root of 1943398661 is about 1247.9215937774.

The spelling of 1943398661 in words is "one billion, nine hundred forty-three million, three hundred ninety-eight thousand, six hundred sixty-one".