21244420 has 24 divisors (see below), whose sum is σ = 44919000. Its totient is φ = 8439552.

The previous prime is 21244417. The next prime is 21244459. The reversal of 21244420 is 2444212.

It can be written as a sum of positive squares in 4 ways, for example, as 614656 + 20629764 = 784^2 + 4542^2 .

It is a super-2 number, since 2×21244420² = 902650762272800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 585 + ... + 6544.

It is an arithmetic number, because the mean of its divisors is an integer number (1871625).

Almost surely, 2^21244420 is an apocalyptic number.

21244420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21244420 is an abundant number, since it is smaller than the sum of its proper divisors (23674580).

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

21244420 is a wasteful number, since it uses less digits than its factorization.

21244420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7287 (or 7285 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 19.

The square root of 21244420 is about 4609.1669529320. The cubic root of 21244420 is about 276.9586665639.

Adding to 21244420 its reverse (2444212), we get a palindrome (23688632).

The spelling of 21244420 in words is "twenty-one million, two hundred forty-four thousand, four hundred twenty".