21113137217 has 16 divisors (see below), whose sum is σ = 21595440000. Its totient is φ = 20636149248.

The previous prime is 21113137181. The next prime is 21113137219. The reversal of 21113137217 is 71273131112.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21113137217 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21113137217.

It is not an unprimeable number, because it can be changed into a prime (21113137219) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13137428 + ... + 13139034.

It is an arithmetic number, because the mean of its divisors is an integer number (1349715000).

Almost surely, 2^21113137217 is an apocalyptic number.

It is an amenable number.

21113137217 is a deficient number, since it is larger than the sum of its proper divisors (482302783).

21113137217 is a wasteful number, since it uses less digits than its factorization.

21113137217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3080.

The product of its digits is 1764, while the sum is 29.

Adding to 21113137217 its reverse (71273131112), we get a palindrome (92386268329).

The spelling of 21113137217 in words is "twenty-one billion, one hundred thirteen million, one hundred thirty-seven thousand, two hundred seventeen".