16821666 has 12 divisors (see below), whose sum is σ = 36446982. Its totient is φ = 5607216.

The previous prime is 16821661. The next prime is 16821677. The reversal of 16821666 is 66612861.

It can be written as a sum of positive squares in only one way, i.e., 13505625 + 3316041 = 3675^2 + 1821^2 .

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 16821666.

It is not an unprimeable number, because it can be changed into a prime (16821661) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 467251 + ... + 467286.

Almost surely, 2^16821666 is an apocalyptic number.

16821666 is an abundant number, since it is smaller than the sum of its proper divisors (19625316).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

16821666 is a wasteful number, since it uses less digits than its factorization.

16821666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 934545 (or 934542 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 16821666 is about 4101.4224361799. The cubic root of 16821666 is about 256.2258850200.

The spelling of 16821666 in words is "sixteen million, eight hundred twenty-one thousand, six hundred sixty-six".