21123255 has 8 divisors (see below), whose sum is σ = 33797232. Its totient is φ = 11265728.

The previous prime is 21123211. The next prime is 21123287. The reversal of 21123255 is 55232112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21123255 - 2⁹ = 21122743 is a prime.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 704094 + ... + 704123.

It is an arithmetic number, because the mean of its divisors is an integer number (4224654).

Almost surely, 2^21123255 is an apocalyptic number.

21123255 is a deficient number, since it is larger than the sum of its proper divisors (12673977).

21123255 is a wasteful number, since it uses less digits than its factorization.

21123255 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1408225.

The product of its digits is 600, while the sum is 21.

The square root of 21123255 is about 4596.0042428179. The cubic root of 21123255 is about 276.4311288672.

Adding to 21123255 its reverse (55232112), we get a palindrome (76355367).

The spelling of 21123255 in words is "twenty-one million, one hundred twenty-three thousand, two hundred fifty-five".