21209553226 has 16 divisors (see below), whose sum is σ = 33688642824. Its totient is φ = 9980112384.

The previous prime is 21209553223. The next prime is 21209553283. The reversal of 21209553226 is 62235590212.

It is a happy number.

It is a Cunningham number, because it is equal to 145635²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 19529783001 + 1679770225 = 139749^2 + 40985^2 .

It is not an unprimeable number, because it can be changed into a prime (21209553223) 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, 569926 + ... + 605998.

Almost surely, 2^21209553226 is an apocalyptic number.

21209553226 is a deficient number, since it is larger than the sum of its proper divisors (12479089598).

21209553226 is a wasteful number, since it uses less digits than its factorization.

21209553226 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53385.

The product of its (nonzero) digits is 64800, while the sum is 37.

The spelling of 21209553226 in words is "twenty-one billion, two hundred nine million, five hundred fifty-three thousand, two hundred twenty-six".