21040505104243 has 16 divisors (see below), whose sum is σ = 22299458176800. Its totient is φ = 19817226123520.

The previous prime is 21040505104219. The next prime is 21040505104259. The reversal of 21040505104243 is 34240150504012.

It is a cyclic number.

It is not a de Polignac number, because 21040505104243 - 2²¹ = 21040503007091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21040505104543) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9482505 + ... + 11489077.

It is an arithmetic number, because the mean of its divisors is an integer number (1393716136050).

Almost surely, 2^{21040505104243} is an apocalyptic number.

21040505104243 is a deficient number, since it is larger than the sum of its proper divisors (1258953072557).

21040505104243 is a wasteful number, since it uses less digits than its factorization.

21040505104243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2015462.

The product of its (nonzero) digits is 19200, while the sum is 31.

Adding to 21040505104243 its reverse (34240150504012), we get a palindrome (55280655608255).

The spelling of 21040505104243 in words is "twenty-one trillion, forty billion, five hundred five million, one hundred four thousand, two hundred forty-three".