20866645 has 4 divisors (see below), whose sum is σ = 25039980. Its totient is φ = 16693312.

The previous prime is 20866639. The next prime is 20866649. The reversal of 20866645 is 54666802.

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 2965284 + 17901361 = 1722^2 + 4231^2 .

It is a cyclic number.

It is not a de Polignac number, because 20866645 - 2⁵ = 20866613 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20866649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2086660 + ... + 2086669.

It is an arithmetic number, because the mean of its divisors is an integer number (6259995).

Almost surely, 2^20866645 is an apocalyptic number.

It is an amenable number.

20866645 is a deficient number, since it is larger than the sum of its proper divisors (4173335).

20866645 is an equidigital number, since it uses as much as digits as its factorization.

20866645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4173334.

The product of its (nonzero) digits is 69120, while the sum is 37.

The square root of 20866645 is about 4568.0022985984. The cubic root of 20866645 is about 275.3071829109.

The spelling of 20866645 in words is "twenty million, eight hundred sixty-six thousand, six hundred forty-five".