21231208 has 32 divisors (see below), whose sum is σ = 43732800. Its totient is φ = 9618048.

The previous prime is 21231173. The next prime is 21231241. The reversal of 21231208 is 80213212.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 460 + ... + 6532.

It is an arithmetic number, because the mean of its divisors is an integer number (1366650).

Almost surely, 2^21231208 is an apocalyptic number.

It is an amenable number.

21231208 is an abundant number, since it is smaller than the sum of its proper divisors (22501592).

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

21231208 is a wasteful number, since it uses less digits than its factorization.

21231208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6121 (or 6117 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 21231208 is about 4607.7334992380. The cubic root of 21231208 is about 276.9012407125.

The spelling of 21231208 in words is "twenty-one million, two hundred thirty-one thousand, two hundred eight".