21225646 has 16 divisors (see below), whose sum is σ = 34524000. Its totient is φ = 9728928.

The previous prime is 21225629. The next prime is 21225649. The reversal of 21225646 is 64652212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21225649) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1135 + ... + 6613.

It is an arithmetic number, because the mean of its divisors is an integer number (2157750).

Almost surely, 2^21225646 is an apocalyptic number.

21225646 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21225646 is a deficient number, since it is larger than the sum of its proper divisors (13298354).

21225646 is a wasteful number, since it uses less digits than its factorization.

21225646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5643.

The product of its digits is 5760, while the sum is 28.

The square root of 21225646 is about 4607.1299091734. The cubic root of 21225646 is about 276.8770583986.

Adding to 21225646 its reverse (64652212), we get a palindrome (85877858).

The spelling of 21225646 in words is "twenty-one million, two hundred twenty-five thousand, six hundred forty-six".