20726665 has 4 divisors (see below), whose sum is σ = 24872004. Its totient is φ = 16581328.

The previous prime is 20726653. The next prime is 20726681. The reversal of 20726665 is 56662702.

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 2 ways, for example, as 2271049 + 18455616 = 1507^2 + 4296^2 .

It is a cyclic number.

It is not a de Polignac number, because 20726665 - 2¹¹ = 20724617 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20726665.

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 in 3 ways as a sum of consecutive naturals, for example, 2072662 + ... + 2072671.

It is an arithmetic number, because the mean of its divisors is an integer number (6218001).

Almost surely, 2^20726665 is an apocalyptic number.

It is an amenable number.

20726665 is a deficient number, since it is larger than the sum of its proper divisors (4145339).

20726665 is an equidigital number, since it uses as much as digits as its factorization.

20726665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4145338.

The product of its (nonzero) digits is 30240, while the sum is 34.

The square root of 20726665 is about 4552.6547200507. The cubic root of 20726665 is about 274.6901855300.

The spelling of 20726665 in words is "twenty million, seven hundred twenty-six thousand, six hundred sixty-five".