1809172 has 6 divisors (see below), whose sum is σ = 3166058. Its totient is φ = 904584.

The previous prime is 1809169. The next prime is 1809173. The reversal of 1809172 is 2719081.

It can be written as a sum of positive squares in only one way, i.e., 1354896 + 454276 = 1164^2 + 674^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 1809172.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1809173) by changing a digit.

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 as a sum of consecutive naturals, namely, 226143 + ... + 226150.

2^1809172 is an apocalyptic number.

It is an amenable number.

1809172 is a deficient number, since it is larger than the sum of its proper divisors (1356886).

1809172 is a wasteful number, since it uses less digits than its factorization.

1809172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 452297 (or 452295 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 1809172 is about 1345.0546457301. The cubic root of 1809172 is about 121.8503046172.

Subtracting 1809172 from its reverse (2719081), we obtain a palindrome (909909).

The spelling of 1809172 in words is "one million, eight hundred nine thousand, one hundred seventy-two".