21540104205 has 16 divisors (see below), whose sum is σ = 36278070720. Its totient is φ = 10883420928.

The previous prime is 21540104197. The next prime is 21540104219. The reversal of 21540104205 is 50240104512.

It is not a de Polignac number, because 21540104205 - 2³ = 21540104197 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37789372 + ... + 37789941.

It is an arithmetic number, because the mean of its divisors is an integer number (2267379420).

Almost surely, 2^21540104205 is an apocalyptic number.

It is an amenable number.

21540104205 is a deficient number, since it is larger than the sum of its proper divisors (14737966515).

21540104205 is a wasteful number, since it uses less digits than its factorization.

21540104205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75579340.

The product of its (nonzero) digits is 1600, while the sum is 24.

Adding to 21540104205 its reverse (50240104512), we get a palindrome (71780208717).

The spelling of 21540104205 in words is "twenty-one billion, five hundred forty million, one hundred four thousand, two hundred five".