21124204111 has 4 divisors (see below), whose sum is σ = 22042647792. Its totient is φ = 20205760432.

The previous prime is 21124204051. The next prime is 21124204133. The reversal of 21124204111 is 11140242112.

It is a happy number.

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-21124204111 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21124204511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 459221806 + ... + 459221851.

It is an arithmetic number, because the mean of its divisors is an integer number (5510661948).

Almost surely, 2^21124204111 is an apocalyptic number.

21124204111 is a deficient number, since it is larger than the sum of its proper divisors (918443681).

21124204111 is an equidigital number, since it uses as much as digits as its factorization.

21124204111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 918443680.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21124204111 its reverse (11140242112), we get a palindrome (32264446223).

The spelling of 21124204111 in words is "twenty-one billion, one hundred twenty-four million, two hundred four thousand, one hundred eleven".