21280163 has 2 divisors, whose sum is σ = 21280164. Its totient is φ = 21280162.

The previous prime is 21280159. The next prime is 21280169. The reversal of 21280163 is 36108212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21280163 - 2² = 21280159 is a prime.

It is not a weakly prime, because it can be changed into another prime (21280169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10640081 + 10640082.

It is an arithmetic number, because the mean of its divisors is an integer number (10640082).

Almost surely, 2^21280163 is an apocalyptic number.

21280163 is a deficient number, since it is larger than the sum of its proper divisors (1).

21280163 is an equidigital number, since it uses as much as digits as its factorization.

21280163 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21280163 is about 4613.0427052001. The cubic root of 21280163 is about 277.1139039869.

Adding to 21280163 its reverse (36108212), we get a palindrome (57388375).

The spelling of 21280163 in words is "twenty-one million, two hundred eighty thousand, one hundred sixty-three".