21251134617 has 16 divisors (see below), whose sum is σ = 28518799680. Its totient is φ = 14075508672.

The previous prime is 21251134549. The next prime is 21251134643. The reversal of 21251134617 is 71643115212.

It is a de Polignac number, because none of the positive numbers 2^k-21251134617 is a prime.

It is a super-2 number, since 2×21251134617² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21251136617) 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, 1807843 + ... + 1819559.

It is an arithmetic number, because the mean of its divisors is an integer number (1782424980).

Almost surely, 2^21251134617 is an apocalyptic number.

It is an amenable number.

21251134617 is a deficient number, since it is larger than the sum of its proper divisors (7267665063).

21251134617 is a wasteful number, since it uses less digits than its factorization.

21251134617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15592.

The product of its digits is 10080, while the sum is 33.

Adding to 21251134617 its reverse (71643115212), we get a palindrome (92894249829).

The spelling of 21251134617 in words is "twenty-one billion, two hundred fifty-one million, one hundred thirty-four thousand, six hundred seventeen".