20172745 has 4 divisors (see below), whose sum is σ = 24207300. Its totient is φ = 16138192.

The previous prime is 20172743. The next prime is 20172781. The reversal of 20172745 is 54727102.

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 13957696 + 6215049 = 3736^2 + 2493^2 .

It is a cyclic number.

It is not a de Polignac number, because 20172745 - 2¹ = 20172743 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20172743) 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, 2017270 + ... + 2017279.

It is an arithmetic number, because the mean of its divisors is an integer number (6051825).

Almost surely, 2^20172745 is an apocalyptic number.

It is an amenable number.

20172745 is a deficient number, since it is larger than the sum of its proper divisors (4034555).

20172745 is an equidigital number, since it uses as much as digits as its factorization.

20172745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4034554.

The product of its (nonzero) digits is 3920, while the sum is 28.

The square root of 20172745 is about 4491.4079084403. The cubic root of 20172745 is about 272.2210258327.

Adding to 20172745 its reverse (54727102), we get a palindrome (74899847).

The spelling of 20172745 in words is "twenty million, one hundred seventy-two thousand, seven hundred forty-five".