21122568221 has 4 divisors (see below), whose sum is σ = 22365072252. Its totient is φ = 19880064192.

The previous prime is 21122568217. The next prime is 21122568227. The reversal of 21122568221 is 12286522112.

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 10304280100 + 10818288121 = 101510^2 + 104011^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122568221 - 2² = 21122568217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122568227) 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, 621251990 + ... + 621252023.

It is an arithmetic number, because the mean of its divisors is an integer number (5591268063).

Almost surely, 2^21122568221 is an apocalyptic number.

It is an amenable number.

21122568221 is a deficient number, since it is larger than the sum of its proper divisors (1242504031).

21122568221 is a wasteful number, since it uses less digits than its factorization.

21122568221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1242504030.

The product of its digits is 7680, while the sum is 32.

The spelling of 21122568221 in words is "twenty-one billion, one hundred twenty-two million, five hundred sixty-eight thousand, two hundred twenty-one".