21131224043 has 4 divisors (see below), whose sum is σ = 22374237240. Its totient is φ = 19888210848.

The previous prime is 21131224039. The next prime is 21131224061. The reversal of 21131224043 is 34042213112.

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 21131224043 - 2² = 21131224039 is a prime.

It is a super-2 number, since 2×21131224043² (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 (21131224943) 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, 621506573 + ... + 621506606.

It is an arithmetic number, because the mean of its divisors is an integer number (5593559310).

Almost surely, 2^21131224043 is an apocalyptic number.

21131224043 is a deficient number, since it is larger than the sum of its proper divisors (1243013197).

21131224043 is a wasteful number, since it uses less digits than its factorization.

21131224043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1243013196.

The product of its (nonzero) digits is 1152, while the sum is 23.

Adding to 21131224043 its reverse (34042213112), we get a palindrome (55173437155).

The spelling of 21131224043 in words is "twenty-one billion, one hundred thirty-one million, two hundred twenty-four thousand, forty-three".