20217666 has 16 divisors (see below), whose sum is σ = 46211904. Its totient is φ = 5776464.

The previous prime is 20217629. The next prime is 20217677. The reversal of 20217666 is 66671202.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 240645 + ... + 240728.

It is an arithmetic number, because the mean of its divisors is an integer number (2888244).

Almost surely, 2^20217666 is an apocalyptic number.

20217666 is an abundant number, since it is smaller than the sum of its proper divisors (25994238).

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

20217666 is a wasteful number, since it uses less digits than its factorization.

20217666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 481385.

The product of its (nonzero) digits is 6048, while the sum is 30.

The square root of 20217666 is about 4496.4058980479. The cubic root of 20217666 is about 272.4229381172.

Adding to 20217666 its reverse (66671202), we get a palindrome (86888868).

The spelling of 20217666 in words is "twenty million, two hundred seventeen thousand, six hundred sixty-six".