21431224321 has 4 divisors (see below), whose sum is σ = 23079780052. Its totient is φ = 19782668592.

The previous prime is 21431224307. The next prime is 21431224337. The reversal of 21431224321 is 12342213412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4107399921 + 17323824400 = 64089^2 + 131620^2 .

It is a cyclic number.

It is not a de Polignac number, because 21431224321 - 2⁷ = 21431224193 is a prime.

It is a super-2 number, since 2×21431224321² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21431224621) 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, 824277846 + ... + 824277871.

It is an arithmetic number, because the mean of its divisors is an integer number (5769945013).

Almost surely, 2^21431224321 is an apocalyptic number.

It is an amenable number.

21431224321 is a deficient number, since it is larger than the sum of its proper divisors (1648555731).

21431224321 is a wasteful number, since it uses less digits than its factorization.

21431224321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1648555730.

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

Adding to 21431224321 its reverse (12342213412), we get a palindrome (33773437733).

The spelling of 21431224321 in words is "twenty-one billion, four hundred thirty-one million, two hundred twenty-four thousand, three hundred twenty-one".