21280223 has 2 divisors, whose sum is σ = 21280224. Its totient is φ = 21280222.

The previous prime is 21280219. The next prime is 21280241. The reversal of 21280223 is 32208212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21280223 - 2² = 21280219 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21280195 and 21280204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21280253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10640111 + 10640112.

It is an arithmetic number, because the mean of its divisors is an integer number (10640112).

Almost surely, 2^21280223 is an apocalyptic number.

21280223 is a deficient number, since it is larger than the sum of its proper divisors (1).

21280223 is an equidigital number, since it uses as much as digits as its factorization.

21280223 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21280223 is about 4613.0492084954. The cubic root of 21280223 is about 277.1141644300.

Adding to 21280223 its reverse (32208212), we get a palindrome (53488435).

The spelling of 21280223 in words is "twenty-one million, two hundred eighty thousand, two hundred twenty-three".