21608378660776 has 64 divisors (see below), whose sum is σ = 42345848250000. Its totient is φ = 10323939225600.

The previous prime is 21608378660773. The next prime is 21608378660777. The reversal of 21608378660776 is 67706687380612.

It can be written as a sum of positive squares in 8 ways, for example, as 6597325812676 + 15011052848100 = 2568526^2 + 3874410^2 .

It is not an unprimeable number, because it can be changed into a prime (21608378660773) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55033600 + ... + 55424848.

Almost surely, 2^{21608378660776} is an apocalyptic number.

It is an amenable number.

21608378660776 is a deficient number, since it is larger than the sum of its proper divisors (20737469589224).

21608378660776 is a wasteful number, since it uses less digits than its factorization.

21608378660776 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393742 (or 393738 counting only the distinct ones).

The product of its (nonzero) digits is 170698752, while the sum is 67.

The spelling of 21608378660776 in words is "twenty-one trillion, six hundred eight billion, three hundred seventy-eight million, six hundred sixty thousand, seven hundred seventy-six".