21122356 has 6 divisors (see below), whose sum is σ = 36964130. Its totient is φ = 10561176.

The previous prime is 21122351. The next prime is 21122359. The reversal of 21122356 is 65322112.

It can be written as a sum of positive squares in only one way, i.e., 20250000 + 872356 = 4500^2 + 934^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2640291 + ... + 2640298.

Almost surely, 2^21122356 is an apocalyptic number.

It is an amenable number.

21122356 is a deficient number, since it is larger than the sum of its proper divisors (15841774).

21122356 is a wasteful number, since it uses less digits than its factorization.

21122356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5280593 (or 5280591 counting only the distinct ones).

The product of its digits is 720, while the sum is 22.

The square root of 21122356 is about 4595.9064394306. The cubic root of 21122356 is about 276.4272072003.

Adding to 21122356 its reverse (65322112), we get a palindrome (86444468).

The spelling of 21122356 in words is "twenty-one million, one hundred twenty-two thousand, three hundred fifty-six".