21255169 has 4 divisors (see below), whose sum is σ = 22890196. Its totient is φ = 19620144.

The previous prime is 21255161. The next prime is 21255203. The reversal of 21255169 is 96155212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7290000 + 13965169 = 2700^2 + 3737^2 .

It is a cyclic number.

It is not a de Polignac number, because 21255169 - 2³ = 21255161 is a prime.

It is a super-2 number, since 2×21255169² = 903564418437122, which contains 22 as substring.

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 21255169.

It is not an unprimeable number, because it can be changed into a prime (21255161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 817494 + ... + 817519.

It is an arithmetic number, because the mean of its divisors is an integer number (5722549).

Almost surely, 2^21255169 is an apocalyptic number.

It is an amenable number.

21255169 is a deficient number, since it is larger than the sum of its proper divisors (1635027).

21255169 is a wasteful number, since it uses less digits than its factorization.

21255169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1635026.

The product of its digits is 5400, while the sum is 31.

The square root of 21255169 is about 4610.3328513243. The cubic root of 21255169 is about 277.0053694433.

The spelling of 21255169 in words is "twenty-one million, two hundred fifty-five thousand, one hundred sixty-nine".