21226020065 has 4 divisors (see below), whose sum is σ = 25471224084. Its totient is φ = 16980816048.

The previous prime is 21226020047. The next prime is 21226020073. The reversal of 21226020065 is 56002062212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13504531681 + 7721488384 = 116209^2 + 87872^2 .

It is a cyclic number.

It is not a de Polignac number, because 21226020065 - 2¹⁰ = 21226019041 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2122602002 + ... + 2122602011.

It is an arithmetic number, because the mean of its divisors is an integer number (6367806021).

Almost surely, 2^21226020065 is an apocalyptic number.

It is an amenable number.

21226020065 is a deficient number, since it is larger than the sum of its proper divisors (4245204019).

21226020065 is an equidigital number, since it uses as much as digits as its factorization.

21226020065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4245204018.

The product of its (nonzero) digits is 2880, while the sum is 26.

Adding to 21226020065 its reverse (56002062212), we get a palindrome (77228082277).

The spelling of 21226020065 in words is "twenty-one billion, two hundred twenty-six million, twenty thousand, sixty-five".