1720420 has 36 divisors (see below), whose sum is σ = 3919860. Its totient is φ = 633984.

The previous prime is 1720399. The next prime is 1720421. The reversal of 1720420 is 240271.

It can be written as a sum of positive squares in 6 ways, for example, as 142884 + 1577536 = 378^2 + 1256^2 .

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 1720394 and 1720403.

It is not an unprimeable number, because it can be changed into a prime (1720421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3126 + ... + 3634.

It is an arithmetic number, because the mean of its divisors is an integer number (108885).

2^1720420 is an apocalyptic number.

1720420 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1720420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1959930).

1720420 is an abundant number, since it is smaller than the sum of its proper divisors (2199440).

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

1720420 is a wasteful number, since it uses less digits than its factorization.

1720420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 544 (or 529 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 16.

The square root of 1720420 is about 1311.6478185855. The cubic root of 1720420 is about 119.8242798495.

Adding to 1720420 its reverse (240271), we get a palindrome (1960691).

The spelling of 1720420 in words is "one million, seven hundred twenty thousand, four hundred twenty".