21431131424 has 12 divisors (see below), whose sum is σ = 42192540054. Its totient is φ = 10715565696.

The previous prime is 21431131417. The next prime is 21431131427. The reversal of 21431131424 is 42413113412.

It can be written as a sum of positive squares in only one way, i.e., 17494823824 + 3936307600 = 132268^2 + 62740^2 .

It is a super-2 number, since 2×21431131424² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21431131393 and 21431131402.

It is not an unprimeable number, because it can be changed into a prime (21431131427) 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 as a sum of consecutive naturals, namely, 334861397 + ... + 334861460.

Almost surely, 2^21431131424 is an apocalyptic number.

It is an amenable number.

21431131424 is a deficient number, since it is larger than the sum of its proper divisors (20761408630).

21431131424 is an equidigital number, since it uses as much as digits as its factorization.

21431131424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 669722867 (or 669722859 counting only the distinct ones).

The product of its digits is 2304, while the sum is 26.

Adding to 21431131424 its reverse (42413113412), we get a palindrome (63844244836).

The spelling of 21431131424 in words is "twenty-one billion, four hundred thirty-one million, one hundred thirty-one thousand, four hundred twenty-four".