1720813 has 4 divisors (see below), whose sum is σ = 1724220. Its totient is φ = 1717408.

The previous prime is 1720799. The next prime is 1720843. The reversal of 1720813 is 3180271.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 459684 + 1261129 = 678^2 + 1123^2 .

It is a cyclic number.

It is not a de Polignac number, because 1720813 - 2⁵ = 1720781 is a prime.

It is a super-2 number, since 2×1720813² = 5922394761938, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1720843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 778 + ... + 2011.

It is an arithmetic number, because the mean of its divisors is an integer number (431055).

2^1720813 is an apocalyptic number.

It is an amenable number.

1720813 is a deficient number, since it is larger than the sum of its proper divisors (3407).

1720813 is an equidigital number, since it uses as much as digits as its factorization.

1720813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3406.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 1720813 is about 1311.7976215865. The cubic root of 1720813 is about 119.8334030785.

The spelling of 1720813 in words is "one million, seven hundred twenty thousand, eight hundred thirteen".