21144305231 has 4 divisors (see below), whose sum is σ = 24164920272. Its totient is φ = 18123690192.

The previous prime is 21144305167. The next prime is 21144305243. The reversal of 21144305231 is 13250344112.

It is a happy number.

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 21144305231 - 2⁶ = 21144305167 is a prime.

It is a super-2 number, since 2×21144305231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21144305231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144305291) 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, 1510307510 + ... + 1510307523.

It is an arithmetic number, because the mean of its divisors is an integer number (6041230068).

Almost surely, 2^21144305231 is an apocalyptic number.

21144305231 is a deficient number, since it is larger than the sum of its proper divisors (3020615041).

21144305231 is an equidigital number, since it uses as much as digits as its factorization.

21144305231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3020615040.

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

Adding to 21144305231 its reverse (13250344112), we get a palindrome (34394649343).

The spelling of 21144305231 in words is "twenty-one billion, one hundred forty-four million, three hundred five thousand, two hundred thirty-one".