21229812 has 18 divisors (see below), whose sum is σ = 53664338. Its totient is φ = 7076592.

The previous prime is 21229777. The next prime is 21229829. The reversal of 21229812 is 21892212.

It can be written as a sum of positive squares in only one way, i.e., 11532816 + 9696996 = 3396^2 + 3114^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

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 5 ways as a sum of consecutive naturals, for example, 294823 + ... + 294894.

Almost surely, 2^21229812 is an apocalyptic number.

It is an amenable number.

21229812 is an abundant number, since it is smaller than the sum of its proper divisors (32434526).

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

21229812 is a wasteful number, since it uses less digits than its factorization.

21229812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 589727 (or 589722 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 21229812 is about 4607.5820122923. The cubic root of 21229812 is about 276.8951716183.

The spelling of 21229812 in words is "twenty-one million, two hundred twenty-nine thousand, eight hundred twelve".