21226405 has 8 divisors (see below), whose sum is σ = 26350200. Its totient is φ = 16395456.

The previous prime is 21226393. The next prime is 21226409. The reversal of 21226405 is 50462212.

It can be written as a sum of positive squares in 4 ways, for example, as 2719201 + 18507204 = 1649^2 + 4302^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21226405 - 2⁷ = 21226277 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21226409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 73050 + ... + 73339.

It is an arithmetic number, because the mean of its divisors is an integer number (3293775).

Almost surely, 2^21226405 is an apocalyptic number.

It is an amenable number.

21226405 is a deficient number, since it is larger than the sum of its proper divisors (5123795).

21226405 is a wasteful number, since it uses less digits than its factorization.

21226405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146423.

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 21226405 is about 4607.2122807615. The cubic root of 21226405 is about 276.8803586072.

Adding to 21226405 its reverse (50462212), we get a palindrome (71688617).

The spelling of 21226405 in words is "twenty-one million, two hundred twenty-six thousand, four hundred five".