21125255 has 8 divisors (see below), whose sum is σ = 25940112. Its totient is φ = 16507008.

The previous prime is 21125239. The next prime is 21125257. The reversal of 21125255 is 55252112.

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 21125255 - 2⁴ = 21125239 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21125255.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125257) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48914 + ... + 49343.

It is an arithmetic number, because the mean of its divisors is an integer number (3242514).

Almost surely, 2^21125255 is an apocalyptic number.

21125255 is a deficient number, since it is larger than the sum of its proper divisors (4814857).

21125255 is an equidigital number, since it uses as much as digits as its factorization.

21125255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98305.

The product of its digits is 1000, while the sum is 23.

The square root of 21125255 is about 4596.2218179718. The cubic root of 21125255 is about 276.4398529774.

Adding to 21125255 its reverse (55252112), we get a palindrome (76377367).

The spelling of 21125255 in words is "twenty-one million, one hundred twenty-five thousand, two hundred fifty-five".