21831208 has 32 divisors (see below), whose sum is σ = 47275200. Its totient is φ = 9257472.

The previous prime is 21831181. The next prime is 21831217. The reversal of 21831208 is 80213812.

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, 3423 + ... + 7441.

It is an arithmetic number, because the mean of its divisors is an integer number (1477350).

Almost surely, 2^21831208 is an apocalyptic number.

21831208 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21831208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23637600).

21831208 is an abundant number, since it is smaller than the sum of its proper divisors (25443992).

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

21831208 is a wasteful number, since it uses less digits than its factorization.

21831208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4129 (or 4125 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 25.

The square root of 21831208 is about 4672.3878263689. The cubic root of 21831208 is about 279.4854836969.

The spelling of 21831208 in words is "twenty-one million, eight hundred thirty-one thousand, two hundred eight".