21273208 has 32 divisors (see below), whose sum is σ = 43954560. Its totient is φ = 9571680.

The previous prime is 21273191. The next prime is 21273253. The reversal of 21273208 is 80237212.

It is a super-2 number, since 2×21273208² = 905098757222528, which contains 22 as substring.

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, 7891 + ... + 10237.

It is an arithmetic number, because the mean of its divisors is an integer number (1373580).

Almost surely, 2^21273208 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21273208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21977280).

21273208 is an abundant number, since it is smaller than the sum of its proper divisors (22681352).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21273208 is a wasteful number, since it uses less digits than its factorization.

21273208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2467 (or 2463 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21273208 is about 4612.2888027529. The cubic root of 21273208 is about 277.0837109661.

It can be divided in two parts, 2127 and 3208, that added together give a palindrome (5335).

The spelling of 21273208 in words is "twenty-one million, two hundred seventy-three thousand, two hundred eight".