20809766 has 4 divisors (see below), whose sum is σ = 31214652. Its totient is φ = 10404882.

The previous prime is 20809759. The next prime is 20809777. The reversal of 20809766 is 66790802.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5202440 + ... + 5202443.

It is an arithmetic number, because the mean of its divisors is an integer number (7803663).

Almost surely, 2^20809766 is an apocalyptic number.

20809766 is a deficient number, since it is larger than the sum of its proper divisors (10404886).

20809766 is a wasteful number, since it uses less digits than its factorization.

20809766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10404885.

The product of its (nonzero) digits is 36288, while the sum is 38.

The square root of 20809766 is about 4561.7722433282. The cubic root of 20809766 is about 275.0568080988.

The spelling of 20809766 in words is "twenty million, eight hundred nine thousand, seven hundred sixty-six".