21087666650 has 24 divisors (see below), whose sum is σ = 39310458300. Its totient is φ = 8416271360.

The previous prime is 21087666577. The next prime is 21087666683. The reversal of 21087666650 is 5666678012.

It can be written as a sum of positive squares in 6 ways, for example, as 8391109609 + 12696557041 = 91603^2 + 112679^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21087666595 and 21087666604.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 447209 + ... + 492108.

Almost surely, 2^21087666650 is an apocalyptic number.

21087666650 is a deficient number, since it is larger than the sum of its proper divisors (18222791650).

21087666650 is a wasteful number, since it uses less digits than its factorization.

21087666650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 939778 (or 939773 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 47.

The spelling of 21087666650 in words is "twenty-one billion, eighty-seven million, six hundred sixty-six thousand, six hundred fifty".