21530243231 has 12 divisors (see below), whose sum is σ = 25049043072. Its totient is φ = 18451798848.

The previous prime is 21530243221. The next prime is 21530243239. The reversal of 21530243231 is 13234203512.

It is a happy number.

It is not a de Polignac number, because 21530243231 - 2¹⁰ = 21530242207 is a prime.

It is a super-2 number, since 2×21530243231² (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 21530243231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530243239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 353666 + ... + 410048.

It is an arithmetic number, because the mean of its divisors is an integer number (2087420256).

Almost surely, 2^21530243231 is an apocalyptic number.

21530243231 is a deficient number, since it is larger than the sum of its proper divisors (3518799841).

21530243231 is an equidigital number, since it uses as much as digits as its factorization.

21530243231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64190 (or 64183 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 26.

Adding to 21530243231 its reverse (13234203512), we get a palindrome (34764446743).

The spelling of 21530243231 in words is "twenty-one billion, five hundred thirty million, two hundred forty-three thousand, two hundred thirty-one".