21226644 has 24 divisors (see below), whose sum is σ = 55032320. Its totient is φ = 7075512.

The previous prime is 21226633. The next prime is 21226663. The reversal of 21226644 is 44662212.

21226644 is a `hidden beast` number, since 2 + 12 + 2 + 6 + 644 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

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, 98164 + ... + 98379.

Almost surely, 2^21226644 is an apocalyptic number.

It is an amenable number.

21226644 is an abundant number, since it is smaller than the sum of its proper divisors (33805676).

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

21226644 is a wasteful number, since it uses less digits than its factorization.

21226644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196556 (or 196548 counting only the distinct ones).

The product of its digits is 4608, while the sum is 27.

The square root of 21226644 is about 4607.2382182822. The cubic root of 21226644 is about 276.8813977871.

Adding to 21226644 its reverse (44662212), we get a palindrome (65888856).

The spelling of 21226644 in words is "twenty-one million, two hundred twenty-six thousand, six hundred forty-four".