1720656 has 80 divisors (see below), whose sum is σ = 5654400. Its totient is φ = 490752.

The previous prime is 1720643. The next prime is 1720669. The reversal of 1720656 is 6560271.

1720656 is a `hidden beast` number, since 1 + 7 + 2 + 0 + 656 = 666.

It is an interprime number because it is at equal distance from previous prime (1720643) and next prime (1720669).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 2740 + ... + 3308.

It is an arithmetic number, because the mean of its divisors is an integer number (70680).

2^1720656 is an apocalyptic number.

1720656 is a gapful number since it is divisible by the number (16) 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 1720656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2827200).

1720656 is an abundant number, since it is smaller than the sum of its proper divisors (3933744).

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

1720656 is a wasteful number, since it uses less digits than its factorization.

1720656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 593 (or 581 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

The square root of 1720656 is about 1311.7377786738. The cubic root of 1720656 is about 119.8297585964.

The spelling of 1720656 in words is "one million, seven hundred twenty thousand, six hundred fifty-six".