21544233231 has 4 divisors (see below), whose sum is σ = 28725644312. Its totient is φ = 14362822152.

The previous prime is 21544233199. The next prime is 21544233233. The reversal of 21544233231 is 13233244512.

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

It is not a de Polignac number, because 21544233231 - 2⁵ = 21544233199 is a prime.

It is a super-2 number, since 2×21544233231² (a number of 21 digits) contains 22 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 (21544233233) 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, 3590705536 + ... + 3590705541.

It is an arithmetic number, because the mean of its divisors is an integer number (7181411078).

Almost surely, 2^21544233231 is an apocalyptic number.

21544233231 is a deficient number, since it is larger than the sum of its proper divisors (7181411081).

21544233231 is an equidigital number, since it uses as much as digits as its factorization.

21544233231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7181411080.

The product of its digits is 17280, while the sum is 30.

Adding to 21544233231 its reverse (13233244512), we get a palindrome (34777477743).

The spelling of 21544233231 in words is "twenty-one billion, five hundred forty-four million, two hundred thirty-three thousand, two hundred thirty-one".