21311144243 has 4 divisors (see below), whose sum is σ = 21325458120. Its totient is φ = 21296830368.

The previous prime is 21311144213. The next prime is 21311144269. The reversal of 21311144243 is 34244111312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21311144243 is a prime.

It is a super-3 number, since 3×21311144243³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21311144203) 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, 7154705 + ... + 7157682.

It is an arithmetic number, because the mean of its divisors is an integer number (5331364530).

Almost surely, 2^21311144243 is an apocalyptic number.

21311144243 is a deficient number, since it is larger than the sum of its proper divisors (14313877).

21311144243 is a wasteful number, since it uses less digits than its factorization.

21311144243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14313876.

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

Adding to 21311144243 its reverse (34244111312), we get a palindrome (55555255555).

The spelling of 21311144243 in words is "twenty-one billion, three hundred eleven million, one hundred forty-four thousand, two hundred forty-three".