It is a tau number, because it is divible by the number of its divisors (168).
It is a congruent number.
It is an unprimeable number.
21646400 is an apocalyptic number.
1646400 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 1646400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3149600).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
1646400 is an equidigital number, since it uses as much as digits as its factorization.
1646400 is an odious number, because the sum of its binary digits is odd.
The square root of 1646400 is about 1283.1211945876. The cubic root of 1646400 is about 118.0805731422.
Multiplying 1646400 by its sum of digits (21), we get a square (34574400 = 58802).
1646400 divided by its sum of digits (21) gives a square (78400 = 2802).
The spelling of 1646400 in words is "one million, six hundred forty-six thousand, four hundred".