21226656 has 48 divisors (see below), whose sum is σ = 60788448. Its totient is φ = 6432000.

The previous prime is 21226633. The next prime is 21226663. The reversal of 21226656 is 65662212.

It is a tau number, because it is divible by the number of its divisors (48).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8995 + ... + 11106.

It is an arithmetic number, because the mean of its divisors is an integer number (1266426).

Almost surely, 2^21226656 is an apocalyptic number.

It is an amenable number.

21226656 is an abundant number, since it is smaller than the sum of its proper divisors (39561792).

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

21226656 is a wasteful number, since it uses less digits than its factorization.

21226656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20125 (or 20117 counting only the distinct ones).

The product of its digits is 8640, while the sum is 30.

The square root of 21226656 is about 4607.2395205806. The cubic root of 21226656 is about 276.8814499633.

Adding to 21226656 its reverse (65662212), we get a palindrome (86888868).

Subtracting 21226656 from its reverse (65662212), we obtain a square (44435556 = 6666²).

It can be divided in two parts, 2122 and 6656, that added together give a palindrome (8778).

The spelling of 21226656 in words is "twenty-one million, two hundred twenty-six thousand, six hundred fifty-six".