1720665705 has 16 divisors (see below), whose sum is σ = 3003344064. Its totient is φ = 834262080.

The previous prime is 1720665689. The next prime is 1720665733. The reversal of 1720665705 is 5075660271.

It is not a de Polignac number, because 1720665705 - 2⁴ = 1720665689 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5213974 + ... + 5214303.

It is an arithmetic number, because the mean of its divisors is an integer number (187709004).

Almost surely, 2^1720665705 is an apocalyptic number.

1720665705 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1720665705 is a deficient number, since it is larger than the sum of its proper divisors (1282678359).

1720665705 is a wasteful number, since it uses less digits than its factorization.

1720665705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10428296.

The product of its (nonzero) digits is 88200, while the sum is 39.

The square root of 1720665705 is about 41480.9077166833. The cubic root of 1720665705 is about 1198.2998388755.

It can be divided in two parts, 172066 and 5705, that added together give a palindrome (177771).

The spelling of 1720665705 in words is "one billion, seven hundred twenty million, six hundred sixty-five thousand, seven hundred five".