21768708305 has 16 divisors (see below), whose sum is σ = 26766681984. Its totient is φ = 16985704320.

The previous prime is 21768708287. The next prime is 21768708319. The reversal of 21768708305 is 50380786712.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-21768708305 is a prime.

It is a super-2 number, since 2×21768708305² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21768708305.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 907172 + ... + 930858.

It is an arithmetic number, because the mean of its divisors is an integer number (1672917624).

Almost surely, 2^21768708305 is an apocalyptic number.

It is an amenable number.

21768708305 is a deficient number, since it is larger than the sum of its proper divisors (4997973679).

21768708305 is a wasteful number, since it uses less digits than its factorization.

21768708305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28216.

The product of its (nonzero) digits is 564480, while the sum is 47.

The spelling of 21768708305 in words is "twenty-one billion, seven hundred sixty-eight million, seven hundred eight thousand, three hundred five".