20420633666 has 16 divisors (see below), whose sum is σ = 31500457656. Its totient is φ = 9921211776.

The previous prime is 20420633641. The next prime is 20420633669. The reversal of 20420633666 is 66633602402.

It can be written as a sum of positive squares in 4 ways, for example, as 20414408641 + 6225025 = 142879^2 + 2495^2 .

It is not an unprimeable number, because it can be changed into a prime (20420633669) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 126251 + ... + 238286.

Almost surely, 2^20420633666 is an apocalyptic number.

20420633666 is a deficient number, since it is larger than the sum of its proper divisors (11079823990).

20420633666 is a wasteful number, since it uses less digits than its factorization.

20420633666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 365333.

The product of its (nonzero) digits is 186624, while the sum is 38.

The spelling of 20420633666 in words is "twenty billion, four hundred twenty million, six hundred thirty-three thousand, six hundred sixty-six".