16643947 has 2 divisors, whose sum is σ = 16643948. Its totient is φ = 16643946.

The previous prime is 16643933. The next prime is 16643971. The reversal of 16643947 is 74934661.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16643947 is a prime.

It is not a weakly prime, because it can be changed into another prime (16643987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8321973 + 8321974.

It is an arithmetic number, because the mean of its divisors is an integer number (8321974).

Almost surely, 2^16643947 is an apocalyptic number.

16643947 is a deficient number, since it is larger than the sum of its proper divisors (1).

16643947 is an equidigital number, since it uses as much as digits as its factorization.

16643947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 40.

The square root of 16643947 is about 4079.6993761796. The cubic root of 16643947 is about 255.3203560513.

The spelling of 16643947 in words is "sixteen million, six hundred forty-three thousand, nine hundred forty-seven".