21131243431 has 8 divisors (see below), whose sum is σ = 21451573760. Its totient is φ = 20811058488.

The previous prime is 21131243401. The next prime is 21131243467. The reversal of 21131243431 is 13434213112.

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

It is a cyclic number.

It is not a de Polignac number, because 21131243431 - 2⁷ = 21131243303 is a prime.

It is a super-2 number, since 2×21131243431² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21131243396 and 21131243405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131243401) 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, 276820 + ... + 344806.

It is an arithmetic number, because the mean of its divisors is an integer number (2681446720).

Almost surely, 2^21131243431 is an apocalyptic number.

21131243431 is a deficient number, since it is larger than the sum of its proper divisors (320330329).

21131243431 is an equidigital number, since it uses as much as digits as its factorization.

21131243431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72693.

The product of its digits is 1728, while the sum is 25.

Adding to 21131243431 its reverse (13434213112), we get a palindrome (34565456543).

The spelling of 21131243431 in words is "twenty-one billion, one hundred thirty-one million, two hundred forty-three thousand, four hundred thirty-one".