21225255 has 16 divisors (see below), whose sum is σ = 34518624. Its totient is φ = 11134080.

The previous prime is 21225233. The next prime is 21225263. The reversal of 21225255 is 55252212.

It is not a de Polignac number, because 21225255 - 2¹⁴ = 21208871 is a prime.

It is a super-2 number, since 2×21225255² = 901022899630050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10684 + ... + 12513.

It is an arithmetic number, because the mean of its divisors is an integer number (2157414).

Almost surely, 2^21225255 is an apocalyptic number.

21225255 is a deficient number, since it is larger than the sum of its proper divisors (13293369).

21225255 is a wasteful number, since it uses less digits than its factorization.

21225255 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23266.

The product of its digits is 2000, while the sum is 24.

The square root of 21225255 is about 4607.0874747502. The cubic root of 21225255 is about 276.8753582604.

Adding to 21225255 its reverse (55252212), we get a palindrome (76477467).

The spelling of 21225255 in words is "twenty-one million, two hundred twenty-five thousand, two hundred fifty-five".