21217999999 has 8 divisors (see below), whose sum is σ = 25675563168. Its totient is φ = 17117041920.

The previous prime is 21217999991. The next prime is 21218000009. The reversal of 21217999999 is 99999971212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21217999999 - 2³ = 21217999991 is a prime.

It is a Duffinian number.

21217999999 is a modest number, since divided by 999999 gives 21217 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21217999991) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 89151142 + ... + 89151379.

It is an arithmetic number, because the mean of its divisors is an integer number (3209445396).

Almost surely, 2^21217999999 is an apocalyptic number.

21217999999 is a deficient number, since it is larger than the sum of its proper divisors (4457563169).

21217999999 is a wasteful number, since it uses less digits than its factorization.

21217999999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178302545.

The product of its digits is 14880348, while the sum is 67.

The spelling of 21217999999 in words is "twenty-one billion, two hundred seventeen million, nine hundred ninety-nine thousand, nine hundred ninety-nine".