1720745565 has 64 divisors (see below), whose sum is σ = 3468165120. Its totient is φ = 707696640.

The previous prime is 1720745539. The next prime is 1720745567. The reversal of 1720745565 is 5655470271.

It is a happy number.

It is not a de Polignac number, because 1720745565 - 2⁹ = 1720745053 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1720745567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 104356 + ... + 119714.

It is an arithmetic number, because the mean of its divisors is an integer number (54190080).

Almost surely, 2^1720745565 is an apocalyptic number.

1720745565 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1720745565 is an abundant number, since it is smaller than the sum of its proper divisors (1747419555).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1720745565 is a wasteful number, since it uses less digits than its factorization.

1720745565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15482.

The product of its (nonzero) digits is 294000, while the sum is 42.

The square root of 1720745565 is about 41481.8703170433. The cubic root of 1720745565 is about 1198.3183771936.

The spelling of 1720745565 in words is "one billion, seven hundred twenty million, seven hundred forty-five thousand, five hundred sixty-five".