6661111643 has 2 divisors, whose sum is σ = 6661111644. Its totient is φ = 6661111642.

The previous prime is 6661111621. The next prime is 6661111697. The reversal of 6661111643 is 3461111666.

6661111643 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6661111643 is a prime.

It is not a weakly prime, because it can be changed into another prime (6661111243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3330555821 + 3330555822.

It is an arithmetic number, because the mean of its divisors is an integer number (3330555822).

Almost surely, 2^6661111643 is an apocalyptic number.

6661111643 is a deficient number, since it is larger than the sum of its proper divisors (1).

6661111643 is an equidigital number, since it uses as much as digits as its factorization.

6661111643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 35.

The square root of 6661111643 is about 81615.6335698008. The cubic root of 6661111643 is about 1881.5491647598.

The spelling of 6661111643 in words is "six billion, six hundred sixty-one million, one hundred eleven thousand, six hundred forty-three".