21034205666 has 8 divisors (see below), whose sum is σ = 31552611804. Its totient is φ = 10516668400.

The previous prime is 21034205641. The next prime is 21034205671. The reversal of 21034205666 is 66650243012.

It is a happy number.

21034205666 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 21031090441 + 3115225 = 145021^2 + 1765^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

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 3 ways as a sum of consecutive naturals, for example, 152885 + ... + 255816.

Almost surely, 2^21034205666 is an apocalyptic number.

21034205666 is a deficient number, since it is larger than the sum of its proper divisors (10518406138).

21034205666 is a wasteful number, since it uses less digits than its factorization.

21034205666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434436.

The product of its (nonzero) digits is 51840, while the sum is 35.

Adding to 21034205666 its reverse (66650243012), we get a palindrome (87684448678).

The spelling of 21034205666 in words is "twenty-one billion, thirty-four million, two hundred five thousand, six hundred sixty-six".