1720605 has 16 divisors (see below), whose sum is σ = 2769984. Its totient is φ = 912000.

The previous prime is 1720603. The next prime is 1720613. The reversal of 1720605 is 5060271.

It is not a de Polignac number, because 1720605 - 2¹ = 1720603 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1720603) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3537 + ... + 3993.

It is an arithmetic number, because the mean of its divisors is an integer number (173124).

2^1720605 is an apocalyptic number.

1720605 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1720605 is a deficient number, since it is larger than the sum of its proper divisors (1049379).

1720605 is a wasteful number, since it uses less digits than its factorization.

1720605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 716.

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 1720605 is about 1311.7183386688. The cubic root of 1720605 is about 119.8285746724.

Adding to 1720605 its reverse (5060271), we get a palindrome (6780876).

The spelling of 1720605 in words is "one million, seven hundred twenty thousand, six hundred five".