20816661 has 8 divisors (see below), whose sum is σ = 27872640. Its totient is φ = 13819232.

The previous prime is 20816659. The next prime is 20816669. The reversal of 20816661 is 16661802.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20816661 - 2¹ = 20816659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20816669) by changing a digit.

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, 13800 + ... + 15233.

It is an arithmetic number, because the mean of its divisors is an integer number (3484080).

Almost surely, 2^20816661 is an apocalyptic number.

It is an amenable number.

20816661 is a deficient number, since it is larger than the sum of its proper divisors (7055979).

20816661 is a wasteful number, since it uses less digits than its factorization.

20816661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29275.

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 20816661 is about 4562.5279177228. The cubic root of 20816661 is about 275.0871833766.

The spelling of 20816661 in words is "twenty million, eight hundred sixteen thousand, six hundred sixty-one".