21255223 has 6 divisors (see below), whose sum is σ = 23363312. Its totient is φ = 19322820.

The previous prime is 21255217. The next prime is 21255239. The reversal of 21255223 is 32255212.

It is a de Polignac number, because none of the positive numbers 2^k-21255223 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21255194 and 21255203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255203) 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 in 5 ways as a sum of consecutive naturals, for example, 87711 + ... + 87952.

Almost surely, 2^21255223 is an apocalyptic number.

21255223 is a deficient number, since it is larger than the sum of its proper divisors (2108089).

21255223 is a wasteful number, since it uses less digits than its factorization.

21255223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175685 (or 175674 counting only the distinct ones).

The product of its digits is 1200, while the sum is 22.

The square root of 21255223 is about 4610.3387077307. The cubic root of 21255223 is about 277.0056040259.

The spelling of 21255223 in words is "twenty-one million, two hundred fifty-five thousand, two hundred twenty-three".