20669665 has 4 divisors (see below), whose sum is σ = 24803604. Its totient is φ = 16535728.

The previous prime is 20669659. The next prime is 20669669. The reversal of 20669665 is 56696602.

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

It can be written as a sum of positive squares in 2 ways, for example, as 13046544 + 7623121 = 3612^2 + 2761^2 .

It is a cyclic number.

It is not a de Polignac number, because 20669665 - 2¹¹ = 20667617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20669669) 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 3 ways as a sum of consecutive naturals, for example, 2066962 + ... + 2066971.

It is an arithmetic number, because the mean of its divisors is an integer number (6200901).

Almost surely, 2^20669665 is an apocalyptic number.

It is an amenable number.

20669665 is a deficient number, since it is larger than the sum of its proper divisors (4133939).

20669665 is an equidigital number, since it uses as much as digits as its factorization.

20669665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4133938.

The product of its (nonzero) digits is 116640, while the sum is 40.

The square root of 20669665 is about 4546.3903264018. The cubic root of 20669665 is about 274.4381476273.

The spelling of 20669665 in words is "twenty million, six hundred sixty-nine thousand, six hundred sixty-five".