21124144205 has 4 divisors (see below), whose sum is σ = 25348973052. Its totient is φ = 16899315360.

The previous prime is 21124144169. The next prime is 21124144309. The reversal of 21124144205 is 50244142112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10416447721 + 10707696484 = 102061^2 + 103478^2 .

It is not a de Polignac number, because 21124144205 - 2⁶ = 21124144141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2112414416 + ... + 2112414425.

It is an arithmetic number, because the mean of its divisors is an integer number (6337243263).

Almost surely, 2^21124144205 is an apocalyptic number.

It is an amenable number.

21124144205 is a deficient number, since it is larger than the sum of its proper divisors (4224828847).

21124144205 is an equidigital number, since it uses as much as digits as its factorization.

21124144205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4224828846.

The product of its (nonzero) digits is 2560, while the sum is 26.

Adding to 21124144205 its reverse (50244142112), we get a palindrome (71368286317).

The spelling of 21124144205 in words is "twenty-one billion, one hundred twenty-four million, one hundred forty-four thousand, two hundred five".