21520441123 has 4 divisors (see below), whose sum is σ = 21523141528. Its totient is φ = 21517740720.

The previous prime is 21520441121. The next prime is 21520441141. The reversal of 21520441123 is 32114402512.

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 21520441123 - 2¹ = 21520441121 is a prime.

It is a super-2 number, since 2×21520441123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21520441121) 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, 1338213 + ... + 1354198.

It is an arithmetic number, because the mean of its divisors is an integer number (5380785382).

Almost surely, 2^21520441123 is an apocalyptic number.

21520441123 is a deficient number, since it is larger than the sum of its proper divisors (2700405).

21520441123 is an equidigital number, since it uses as much as digits as its factorization.

21520441123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2700404.

The product of its (nonzero) digits is 1920, while the sum is 25.

Adding to 21520441123 its reverse (32114402512), we get a palindrome (53634843635).

The spelling of 21520441123 in words is "twenty-one billion, five hundred twenty million, four hundred forty-one thousand, one hundred twenty-three".