21225566321 has 4 divisors (see below), whose sum is σ = 21253830144. Its totient is φ = 21197302500.

The previous prime is 21225566309. The next prime is 21225566347. The reversal of 21225566321 is 12366552212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21225566321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21225596321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14130785 + ... + 14132286.

It is an arithmetic number, because the mean of its divisors is an integer number (5313457536).

Almost surely, 2^21225566321 is an apocalyptic number.

It is an amenable number.

21225566321 is a deficient number, since it is larger than the sum of its proper divisors (28263823).

21225566321 is an equidigital number, since it uses as much as digits as its factorization.

21225566321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28263822.

The product of its digits is 43200, while the sum is 35.

The spelling of 21225566321 in words is "twenty-one billion, two hundred twenty-five million, five hundred sixty-six thousand, three hundred twenty-one".