21100340243 has 4 divisors (see below), whose sum is σ = 21112149720. Its totient is φ = 21088530768.

The previous prime is 21100340221. The next prime is 21100340269. The reversal of 21100340243 is 34204300112.

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 21100340243 - 2³⁰ = 20026598419 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21100340213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5902058 + ... + 5905631.

It is an arithmetic number, because the mean of its divisors is an integer number (5278037430).

Almost surely, 2^21100340243 is an apocalyptic number.

21100340243 is a deficient number, since it is larger than the sum of its proper divisors (11809477).

21100340243 is a wasteful number, since it uses less digits than its factorization.

21100340243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11809476.

The product of its (nonzero) digits is 576, while the sum is 20.

Adding to 21100340243 its reverse (34204300112), we get a palindrome (55304640355).

The spelling of 21100340243 in words is "twenty-one billion, one hundred million, three hundred forty thousand, two hundred forty-three".