21121205127 has 16 divisors (see below), whose sum is σ = 32528915712. Its totient is φ = 12047745920.

The previous prime is 21121205099. The next prime is 21121205129. The reversal of 21121205127 is 72150212112.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21121205127 is a prime.

It is a super-2 number, since 2×21121205127² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21121205097 and 21121205106.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121205129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18824043 + ... + 18825164.

It is an arithmetic number, because the mean of its divisors is an integer number (2033057232).

Almost surely, 2^21121205127 is an apocalyptic number.

21121205127 is a deficient number, since it is larger than the sum of its proper divisors (11407710585).

21121205127 is a wasteful number, since it uses less digits than its factorization.

21121205127 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37649238.

The product of its (nonzero) digits is 560, while the sum is 24.

Adding to 21121205127 its reverse (72150212112), we get a palindrome (93271417239).

The spelling of 21121205127 in words is "twenty-one billion, one hundred twenty-one million, two hundred five thousand, one hundred twenty-seven".