21225656 has 16 divisors (see below), whose sum is σ = 42139440. Its totient is φ = 9988480.

The previous prime is 21225653. The next prime is 21225661. The reversal of 21225656 is 65652212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21225653) 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 3 ways as a sum of consecutive naturals, for example, 77900 + ... + 78171.

It is an arithmetic number, because the mean of its divisors is an integer number (2633715).

Almost surely, 2^21225656 is an apocalyptic number.

It is an amenable number.

21225656 is a deficient number, since it is larger than the sum of its proper divisors (20913784).

21225656 is a wasteful number, since it uses less digits than its factorization.

21225656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156094 (or 156090 counting only the distinct ones).

The product of its digits is 7200, while the sum is 29.

The square root of 21225656 is about 4607.1309944476. The cubic root of 21225656 is about 276.8771018801.

Adding to 21225656 its reverse (65652212), we get a palindrome (86877868).

The spelling of 21225656 in words is "twenty-one million, two hundred twenty-five thousand, six hundred fifty-six".