21280873 has 2 divisors, whose sum is σ = 21280874. Its totient is φ = 21280872.

The previous prime is 21280843. The next prime is 21280891. The reversal of 21280873 is 37808212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16096144 + 5184729 = 4012^2 + 2277^2 .

It is a cyclic number.

It is not a de Polignac number, because 21280873 - 2⁵ = 21280841 is a prime.

It is not a weakly prime, because it can be changed into another prime (21280823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10640436 + 10640437.

It is an arithmetic number, because the mean of its divisors is an integer number (10640437).

Almost surely, 2^21280873 is an apocalyptic number.

It is an amenable number.

21280873 is a deficient number, since it is larger than the sum of its proper divisors (1).

21280873 is an equidigital number, since it uses as much as digits as its factorization.

21280873 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 21280873 is about 4613.1196602733. The cubic root of 21280873 is about 277.1169858662.

The spelling of 21280873 in words is "twenty-one million, two hundred eighty thousand, eight hundred seventy-three".