21666420545506 has 8 divisors (see below), whose sum is σ = 35454142710864. Its totient is φ = 9848372975220.

The previous prime is 21666420545491. The next prime is 21666420545537. The reversal of 21666420545506 is 60554502466612.

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 492418648740 + ... + 492418648783.

It is an arithmetic number, because the mean of its divisors is an integer number (4431767838858).

Almost surely, 2^{21666420545506} is an apocalyptic number.

21666420545506 is a deficient number, since it is larger than the sum of its proper divisors (13787722165358).

21666420545506 is a wasteful number, since it uses less digits than its factorization.

21666420545506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 984837297536.

The product of its (nonzero) digits is 10368000, while the sum is 52.

The spelling of 21666420545506 in words is "twenty-one trillion, six hundred sixty-six billion, four hundred twenty million, five hundred forty-five thousand, five hundred six".