21208244 has 12 divisors (see below), whose sum is σ = 37159584. Its totient is φ = 10591224.

The previous prime is 21208183. The next prime is 21208259. The reversal of 21208244 is 44280212.

It is a happy number.

It is a super-2 number, since 2×21208244² = 899579227127072, 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 3 ways as a sum of consecutive naturals, for example, 1127 + ... + 6609.

It is an arithmetic number, because the mean of its divisors is an integer number (3096632).

Almost surely, 2^21208244 is an apocalyptic number.

It is an amenable number.

21208244 is a deficient number, since it is larger than the sum of its proper divisors (15951340).

21208244 is a wasteful number, since it uses less digits than its factorization.

21208244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6454 (or 6452 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 23.

The square root of 21208244 is about 4605.2409274651. The cubic root of 21208244 is about 276.8013711550.

Adding to 21208244 its reverse (44280212), we get a palindrome (65488456).

The spelling of 21208244 in words is "twenty-one million, two hundred eight thousand, two hundred forty-four".