1646640 has 60 divisors (see below), whose sum is σ = 5532384. Its totient is φ = 438912.

The previous prime is 1646633. The next prime is 1646641. The reversal of 1646640 is 466461.

1646640 is a `hidden beast` number, since 16 + 4 + 6 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (60).

It is a super-2 number, since 2×1646640² = 5422846579200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1646641) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 424 + ... + 1863.

2^1646640 is an apocalyptic number.

1646640 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 1646640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2766192).

1646640 is an abundant number, since it is smaller than the sum of its proper divisors (3885744).

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

1646640 is a wasteful number, since it uses less digits than its factorization.

1646640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2306 (or 2297 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 1646640 is about 1283.2147131326. The cubic root of 1646640 is about 118.0863105006.

It can be divided in two parts, 16 and 46640, that added together give a 6-th power (46656 = 6⁶).

The spelling of 1646640 in words is "one million, six hundred forty-six thousand, six hundred forty".