1638660 has 48 divisors (see below), whose sum is σ = 4741632. Its totient is φ = 422400.

The previous prime is 1638653. The next prime is 1638673. The reversal of 1638660 is 668361.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1420 + ... + 2300.

It is an arithmetic number, because the mean of its divisors is an integer number (98784).

2^1638660 is an apocalyptic number.

1638660 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 1638660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2370816).

1638660 is an abundant number, since it is smaller than the sum of its proper divisors (3102972).

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

1638660 is a wasteful number, since it uses less digits than its factorization.

1638660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 924 (or 922 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 1638660 is about 1280.1015584710. The cubic root of 1638660 is about 117.8952436175.

Subtracting from 1638660 its reverse (668361), we obtain a cube (970299 = 99³).

The spelling of 1638660 in words is "one million, six hundred thirty-eight thousand, six hundred sixty".