21785608766 has 16 divisors (see below), whose sum is σ = 35253518544. Its totient is φ = 10058615424.

The previous prime is 21785608703. The next prime is 21785608771. The reversal of 21785608766 is 66780658712.

It is a super-2 number, since 2×21785608766² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6043040 + ... + 6046643.

It is an arithmetic number, because the mean of its divisors is an integer number (2203344909).

Almost surely, 2^21785608766 is an apocalyptic number.

21785608766 is a deficient number, since it is larger than the sum of its proper divisors (13467909778).

21785608766 is a wasteful number, since it uses less digits than its factorization.

21785608766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12089755.

The product of its (nonzero) digits is 6773760, while the sum is 56.

The spelling of 21785608766 in words is "twenty-one billion, seven hundred eighty-five million, six hundred eight thousand, seven hundred sixty-six".