1720645 has 16 divisors (see below), whose sum is σ = 2166912. Its totient is φ = 1310400.

The previous prime is 1720643. The next prime is 1720669. The reversal of 1720645 is 5460271.

It is not a de Polignac number, because 1720645 - 2¹ = 1720643 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1720643) 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, 11320 + ... + 11470.

It is an arithmetic number, because the mean of its divisors is an integer number (135432).

2^1720645 is an apocalyptic number.

It is an amenable number.

1720645 is a deficient number, since it is larger than the sum of its proper divisors (446267).

1720645 is a wasteful number, since it uses less digits than its factorization.

1720645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252.

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 1720645 is about 1311.7335857559. The cubic root of 1720645 is about 119.8295032422.

The spelling of 1720645 in words is "one million, seven hundred twenty thousand, six hundred forty-five".