21680003 has 2 divisors, whose sum is σ = 21680004. Its totient is φ = 21680002.

The previous prime is 21679979. The next prime is 21680017. The reversal of 21680003 is 30008612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21680003 - 2²⁴ = 4902787 is a prime.

It is not a weakly prime, because it can be changed into another prime (21680093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10840001 + 10840002.

It is an arithmetic number, because the mean of its divisors is an integer number (10840002).

Almost surely, 2^21680003 is an apocalyptic number.

21680003 is a deficient number, since it is larger than the sum of its proper divisors (1).

21680003 is an equidigital number, since it uses as much as digits as its factorization.

21680003 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21680003 is about 4656.1790128817. The cubic root of 21680003 is about 278.8387406738.

Adding to 21680003 its reverse (30008612), we get a palindrome (51688615).

The spelling of 21680003 in words is "twenty-one million, six hundred eighty thousand, three".