1688720 has 80 divisors (see below), whose sum is σ = 4553280. Its totient is φ = 576000.

The previous prime is 1688681. The next prime is 1688741. The reversal of 1688720 is 278861.

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16670 + ... + 16770.

It is an arithmetic number, because the mean of its divisors is an integer number (56916).

2^1688720 is an apocalyptic number.

1688720 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 1688720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2276640).

1688720 is an abundant number, since it is smaller than the sum of its proper divisors (2864560).

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

1688720 is a wasteful number, since it uses less digits than its factorization.

1688720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144 (or 138 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 1688720 is about 1299.5075990543. The cubic root of 1688720 is about 119.0837627905.

It can be divided in two parts, 168 and 8720, that added together give a palindrome (8888).

The spelling of 1688720 in words is "one million, six hundred eighty-eight thousand, seven hundred twenty".