1720161 has 12 divisors (see below), whose sum is σ = 2505360. Its totient is φ = 1137240.

The previous prime is 1720157. The next prime is 1720163. The reversal of 1720161 is 1610271.

It is not a de Polignac number, because 1720161 - 2² = 1720157 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1720163) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 450 + ... + 1908.

It is an arithmetic number, because the mean of its divisors is an integer number (208780).

2^1720161 is an apocalyptic number.

It is an amenable number.

1720161 is a deficient number, since it is larger than the sum of its proper divisors (785199).

1720161 is a wasteful number, since it uses less digits than its factorization.

1720161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1596 (or 1593 counting only the distinct ones).

The product of its (nonzero) digits is 84, while the sum is 18.

The square root of 1720161 is about 1311.5490840986. The cubic root of 1720161 is about 119.8182665803.

It can be divided in two parts, 1720 and 161, that added together give a palindrome (1881).

The spelling of 1720161 in words is "one million, seven hundred twenty thousand, one hundred sixty-one".