21531442231 has 8 divisors (see below), whose sum is σ = 23625211680. Its totient is φ = 19500173472.

The previous prime is 21531442193. The next prime is 21531442253. The reversal of 21531442231 is 13224413512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21531442231 - 2⁹ = 21531441719 is a prime.

It is a super-2 number, since 2×21531442231² (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 21531442231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531442931) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15624451 + ... + 15625828.

It is an arithmetic number, because the mean of its divisors is an integer number (2953151460).

Almost surely, 2^21531442231 is an apocalyptic number.

21531442231 is a deficient number, since it is larger than the sum of its proper divisors (2093769449).

21531442231 is a wasteful number, since it uses less digits than its factorization.

21531442231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31250345.

The product of its digits is 5760, while the sum is 28.

Adding to 21531442231 its reverse (13224413512), we get a palindrome (34755855743).

The spelling of 21531442231 in words is "twenty-one billion, five hundred thirty-one million, four hundred forty-two thousand, two hundred thirty-one".