21143204431 has 4 divisors (see below), whose sum is σ = 21147098632. Its totient is φ = 21139310232.

The previous prime is 21143204429. The next prime is 21143204441. The reversal of 21143204431 is 13440234112.

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 21143204431 - 2¹ = 21143204429 is a prime.

It is a super-2 number, since 2×21143204431² (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 = 21143204396 and 21143204405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21143204441) 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, 1938945 + ... + 1949818.

It is an arithmetic number, because the mean of its divisors is an integer number (5286774658).

Almost surely, 2^21143204431 is an apocalyptic number.

21143204431 is a deficient number, since it is larger than the sum of its proper divisors (3894201).

21143204431 is an equidigital number, since it uses as much as digits as its factorization.

21143204431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3894200.

The product of its (nonzero) digits is 2304, while the sum is 25.

Adding to 21143204431 its reverse (13440234112), we get a palindrome (34583438543).

The spelling of 21143204431 in words is "twenty-one billion, one hundred forty-three million, two hundred four thousand, four hundred thirty-one".