20172644 has 6 divisors (see below), whose sum is σ = 35302134. Its totient is φ = 10086320.

The previous prime is 20172643. The next prime is 20172667. The reversal of 20172644 is 44627102.

20172644 is nontrivially palindromic in base 14.

It can be written as a sum of positive squares in only one way, i.e., 20160100 + 12544 = 4490^2 + 112^2 .

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 as a sum of consecutive naturals, namely, 2521577 + ... + 2521584.

It is an arithmetic number, because the mean of its divisors is an integer number (5883689).

Almost surely, 2^20172644 is an apocalyptic number.

It is an amenable number.

20172644 is a deficient number, since it is larger than the sum of its proper divisors (15129490).

20172644 is a wasteful number, since it uses less digits than its factorization.

20172644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5043165 (or 5043163 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 26.

The square root of 20172644 is about 4491.3966647358. The cubic root of 20172644 is about 272.2205715173.

Adding to 20172644 its reverse (44627102), we get a palindrome (64799746).

The spelling of 20172644 in words is "twenty million, one hundred seventy-two thousand, six hundred forty-four".