21103643866 has 16 divisors (see below), whose sum is σ = 32082561000. Its totient is φ = 10409986048.

The previous prime is 21103643863. The next prime is 21103643879. The reversal of 21103643866 is 66834630112.

It can be written as a sum of positive squares in 4 ways, for example, as 14756175625 + 6347468241 = 121475^2 + 79671^2 .

It is not an unprimeable number, because it can be changed into a prime (21103643863) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52105 + ... + 211948.

Almost surely, 2^21103643866 is an apocalyptic number.

21103643866 is a deficient number, since it is larger than the sum of its proper divisors (10978917134).

21103643866 is a wasteful number, since it uses less digits than its factorization.

21103643866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264593.

The product of its (nonzero) digits is 124416, while the sum is 40.

The spelling of 21103643866 in words is "twenty-one billion, one hundred three million, six hundred forty-three thousand, eight hundred sixty-six".