21214206664666 has 4 divisors (see below), whose sum is σ = 31821309997002. Its totient is φ = 10607103332332.

The previous prime is 21214206664633. The next prime is 21214206664667. The reversal of 21214206664666 is 66646660241212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20403099286441 + 811107378225 = 4516979^2 + 900615^2 .

It is a super-3 number, since 3×21214206664666³ (a number of 41 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (21214206664667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5303551666165 + ... + 5303551666168.

Almost surely, 2^{21214206664666} is an apocalyptic number.

21214206664666 is a deficient number, since it is larger than the sum of its proper divisors (10607103332336).

21214206664666 is a wasteful number, since it uses less digits than its factorization.

21214206664666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10607103332335.

The product of its (nonzero) digits is 5971968, while the sum is 52.

The spelling of 21214206664666 in words is "twenty-one trillion, two hundred fourteen billion, two hundred six million, six hundred sixty-four thousand, six hundred sixty-six".