16665643 has 2 divisors, whose sum is σ = 16665644. Its totient is φ = 16665642.

The previous prime is 16665637. The next prime is 16665673. The reversal of 16665643 is 34656661.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16665643 is a prime.

It is not a weakly prime, because it can be changed into another prime (16665613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8332821 + 8332822.

It is an arithmetic number, because the mean of its divisors is an integer number (8332822).

Almost surely, 2^16665643 is an apocalyptic number.

16665643 is a deficient number, since it is larger than the sum of its proper divisors (1).

16665643 is an equidigital number, since it uses as much as digits as its factorization.

16665643 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 16665643 is about 4082.3575296635. The cubic root of 16665643 is about 255.4312477213.

The spelling of 16665643 in words is "sixteen million, six hundred sixty-five thousand, six hundred forty-three".