20009666 has 4 divisors (see below), whose sum is σ = 30014502. Its totient is φ = 10004832.

The previous prime is 20009659. The next prime is 20009677. The reversal of 20009666 is 66690002.

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., 19936225 + 73441 = 4465^2 + 271^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5002415 + ... + 5002418.

Almost surely, 2^20009666 is an apocalyptic number.

20009666 is a deficient number, since it is larger than the sum of its proper divisors (10004836).

20009666 is a wasteful number, since it uses less digits than its factorization.

20009666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10004835.

The product of its (nonzero) digits is 3888, while the sum is 29.

The square root of 20009666 is about 4473.2165161101. The cubic root of 20009666 is about 271.4854838844.

Adding to 20009666 its reverse (66690002), we get a palindrome (86699668).

The spelling of 20009666 in words is "twenty million, nine thousand, six hundred sixty-six".