21220936 has 32 divisors (see below), whose sum is σ = 43721280. Its totient is φ = 9576000.

The previous prime is 21220921. The next prime is 21220937. The reversal of 21220936 is 63902212.

21220936 = 256² + 257² + ... + 431².

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21220936.

It is not an unprimeable number, because it can be changed into a prime (21220937) by changing a digit.

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, 12490 + ... + 14086.

It is an arithmetic number, because the mean of its divisors is an integer number (1366290).

Almost surely, 2^21220936 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 21220936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21860640).

21220936 is an abundant number, since it is smaller than the sum of its proper divisors (22500344).

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

21220936 is a wasteful number, since it uses less digits than its factorization.

21220936 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1765 (or 1761 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 21220936 is about 4606.6187165860. The cubic root of 21220936 is about 276.8565770837.

The spelling of 21220936 in words is "twenty-one million, two hundred twenty thousand, nine hundred thirty-six".