20816786 has 4 divisors (see below), whose sum is σ = 31225182. Its totient is φ = 10408392.

The previous prime is 20816777. The next prime is 20816791. The reversal of 20816786 is 68761802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 68761802 = 2 ⋅34380901.

It can be written as a sum of positive squares in only one way, i.e., 18757561 + 2059225 = 4331^2 + 1435^2 .

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 as a sum of consecutive naturals, namely, 5204195 + ... + 5204198.

Almost surely, 2^20816786 is an apocalyptic number.

20816786 is a deficient number, since it is larger than the sum of its proper divisors (10408396).

20816786 is a wasteful number, since it uses less digits than its factorization.

20816786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10408395.

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 20816786 is about 4562.5416162486. The cubic root of 20816786 is about 275.0877339905.

The spelling of 20816786 in words is "twenty million, eight hundred sixteen thousand, seven hundred eighty-six".