20172645 has 24 divisors (see below), whose sum is σ = 36263136. Its totient is φ = 10758096.

The previous prime is 20172643. The next prime is 20172667. The reversal of 20172645 is 54627102.

20172645 is a `hidden beast` number, since 2 + 0 + 17 + 2 + 645 = 666.

It is not a de Polignac number, because 20172645 - 2¹ = 20172643 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20172641) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7087 + ... + 9516.

It is an arithmetic number, because the mean of its divisors is an integer number (1510964).

Almost surely, 2^20172645 is an apocalyptic number.

It is an amenable number.

20172645 is a deficient number, since it is larger than the sum of its proper divisors (16090491).

20172645 is an equidigital number, since it uses as much as digits as its factorization.

20172645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16623 (or 16611 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

The square root of 20172645 is about 4491.3967760598. The cubic root of 20172645 is about 272.2205760155.

Adding to 20172645 its reverse (54627102), we get a palindrome (74799747).

The spelling of 20172645 in words is "twenty million, one hundred seventy-two thousand, six hundred forty-five".