21660540506206 has 8 divisors (see below), whose sum is σ = 37132355153520. Its totient is φ = 9283088788368.

The previous prime is 21660540506173. The next prime is 21660540506221. The reversal of 21660540506206 is 60260504506612.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 773590732351 + ... + 773590732378.

It is an arithmetic number, because the mean of its divisors is an integer number (4641544394190).

Almost surely, 2^{21660540506206} is an apocalyptic number.

21660540506206 is a deficient number, since it is larger than the sum of its proper divisors (15471814647314).

21660540506206 is a wasteful number, since it uses less digits than its factorization.

21660540506206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1547181464738.

The product of its (nonzero) digits is 518400, while the sum is 43.

The spelling of 21660540506206 in words is "twenty-one trillion, six hundred sixty billion, five hundred forty million, five hundred six thousand, two hundred six".