1720820 has 24 divisors (see below), whose sum is σ = 3645600. Its totient is φ = 682272.

The previous prime is 1720799. The next prime is 1720843. The reversal of 1720820 is 280271.

It is a super-2 number, since 2×1720820² = 5922442944800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 1720792 and 1720801.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2471 + ... + 3089.

It is an arithmetic number, because the mean of its divisors is an integer number (151900).

2^1720820 is an apocalyptic number.

1720820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1720820 is an abundant number, since it is smaller than the sum of its proper divisors (1924780).

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

1720820 is a wasteful number, since it uses less digits than its factorization.

1720820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 767 (or 765 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 1720820 is about 1311.8002896783. The cubic root of 1720820 is about 119.8335655662.

The spelling of 1720820 in words is "one million, seven hundred twenty thousand, eight hundred twenty".