21571445221 has 16 divisors (see below), whose sum is σ = 22621248000. Its totient is φ = 20550803328.

The previous prime is 21571445219. The next prime is 21571445239. The reversal of 21571445221 is 12254417512.

It is a cyclic number.

It is not a de Polignac number, because 21571445221 - 2¹ = 21571445219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21571445261) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 307380 + ... + 370978.

It is an arithmetic number, because the mean of its divisors is an integer number (1413828000).

Almost surely, 2^21571445221 is an apocalyptic number.

It is an amenable number.

21571445221 is a deficient number, since it is larger than the sum of its proper divisors (1049802779).

21571445221 is a wasteful number, since it uses less digits than its factorization.

21571445221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63828.

The product of its digits is 22400, while the sum is 34.

The spelling of 21571445221 in words is "twenty-one billion, five hundred seventy-one million, four hundred forty-five thousand, two hundred twenty-one".