16661563 has 2 divisors, whose sum is σ = 16661564. Its totient is φ = 16661562.

The previous prime is 16661531. The next prime is 16661599. The reversal of 16661563 is 36516661.

It is a weak prime.

It is an emirp because it is prime and its reverse (36516661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16661563 - 2⁵ = 16661531 is a prime.

It is not a weakly prime, because it can be changed into another prime (16661363) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8330781 + 8330782.

It is an arithmetic number, because the mean of its divisors is an integer number (8330782).

Almost surely, 2^16661563 is an apocalyptic number.

16661563 is a deficient number, since it is larger than the sum of its proper divisors (1).

16661563 is an equidigital number, since it uses as much as digits as its factorization.

16661563 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 34.

The square root of 16661563 is about 4081.8577878216. The cubic root of 16661563 is about 255.4104015500.

The spelling of 16661563 in words is "sixteen million, six hundred sixty-one thousand, five hundred sixty-three".