21288273 has 4 divisors (see below), whose sum is σ = 28384368. Its totient is φ = 14192180.

The previous prime is 21288259. The next prime is 21288343. The reversal of 21288273 is 37288212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21288273 - 2¹⁰ = 21287249 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21288173) 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 3 ways as a sum of consecutive naturals, for example, 3548043 + ... + 3548048.

It is an arithmetic number, because the mean of its divisors is an integer number (7096092).

Almost surely, 2^21288273 is an apocalyptic number.

It is an amenable number.

21288273 is a deficient number, since it is larger than the sum of its proper divisors (7096095).

21288273 is an equidigital number, since it uses as much as digits as its factorization.

21288273 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7096094.

The product of its digits is 10752, while the sum is 33.

The square root of 21288273 is about 4613.9216508302. The cubic root of 21288273 is about 277.1491027825.

It can be divided in two parts, 2128 and 8273, that added together give a palindrome (10401).

The spelling of 21288273 in words is "twenty-one million, two hundred eighty-eight thousand, two hundred seventy-three".