1638720 has 84 divisors (see below), whose sum is σ = 5646420. Its totient is φ = 436224.

The previous prime is 1638719. The next prime is 1638733. The reversal of 1638720 is 278361.

1638720 is a `hidden beast` number, since 1 + 638 + 7 + 20 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 419904 + 1218816 = 648^2 + 1104^2 .

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 2596 + ... + 3164.

2^1638720 is an apocalyptic number.

1638720 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 1638720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2823210).

1638720 is an abundant number, since it is smaller than the sum of its proper divisors (4007700).

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

1638720 is a wasteful number, since it uses less digits than its factorization.

1638720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 592 (or 579 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 1638720 is about 1280.1249938971. The cubic root of 1638720 is about 117.8966825225.

The spelling of 1638720 in words is "one million, six hundred thirty-eight thousand, seven hundred twenty".