21557224471 has 4 divisors (see below), whose sum is σ = 21595111200. Its totient is φ = 21519337744.

The previous prime is 21557224453. The next prime is 21557224517. The reversal of 21557224471 is 17442275512.

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

It is a cyclic number.

It is not a de Polignac number, because 21557224471 - 2⁷ = 21557224343 is a prime.

It is a super-3 number, since 3×21557224471³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21557224771) 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, 18942511 + ... + 18943648.

It is an arithmetic number, because the mean of its divisors is an integer number (5398777800).

Almost surely, 2^21557224471 is an apocalyptic number.

21557224471 is a deficient number, since it is larger than the sum of its proper divisors (37886729).

21557224471 is an equidigital number, since it uses as much as digits as its factorization.

21557224471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37886728.

The product of its digits is 156800, while the sum is 40.

Adding to 21557224471 its reverse (17442275512), we get a palindrome (38999499983).

The spelling of 21557224471 in words is "twenty-one billion, five hundred fifty-seven million, two hundred twenty-four thousand, four hundred seventy-one".