1720609 has 4 divisors (see below), whose sum is σ = 1877040. Its totient is φ = 1564180.

The previous prime is 1720603. The next prime is 1720613. The reversal of 1720609 is 9060271.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1720609 - 2¹⁷ = 1589537 is a prime.

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

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 78199 + ... + 78220.

It is an arithmetic number, because the mean of its divisors is an integer number (469260).

2^1720609 is an apocalyptic number.

It is an amenable number.

1720609 is a deficient number, since it is larger than the sum of its proper divisors (156431).

1720609 is a wasteful number, since it uses less digits than its factorization.

1720609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156430.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 1720609 is about 1311.7198633855. The cubic root of 1720609 is about 119.8286675300.

The spelling of 1720609 in words is "one million, seven hundred twenty thousand, six hundred nine".