21695217808 has 40 divisors (see below), whose sum is σ = 46501684416. Its totient is φ = 9722563200.

The previous prime is 21695217779. The next prime is 21695217809. The reversal of 21695217808 is 80871259612.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21695217809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 855591 + ... + 880582.

Almost surely, 2^21695217808 is an apocalyptic number.

It is an amenable number.

21695217808 is an abundant number, since it is smaller than the sum of its proper divisors (24806466608).

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

21695217808 is a wasteful number, since it uses less digits than its factorization.

21695217808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1736263 (or 1736257 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 49.

The spelling of 21695217808 in words is "twenty-one billion, six hundred ninety-five million, two hundred seventeen thousand, eight hundred eight".