21717216872 has 16 divisors (see below), whose sum is σ = 43852072740. Its totient is φ = 10023330816.

The previous prime is 21717216793. The next prime is 21717216887. The reversal of 21717216872 is 27861271712.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21542607076 + 174609796 = 146774^2 + 13214^2 .

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 104409593 + ... + 104409800.

Almost surely, 2^21717216872 is an apocalyptic number.

It is an amenable number.

21717216872 is an abundant number, since it is smaller than the sum of its proper divisors (22134855868).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21717216872 is a wasteful number, since it uses less digits than its factorization.

21717216872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208819412 (or 208819408 counting only the distinct ones).

The product of its digits is 131712, while the sum is 44.

The spelling of 21717216872 in words is "twenty-one billion, seven hundred seventeen million, two hundred sixteen thousand, eight hundred seventy-two".