1638340 has 36 divisors (see below), whose sum is σ = 3787308. Its totient is φ = 594880.

The previous prime is 1638331. The next prime is 1638347. The reversal of 1638340 is 438361.

1638340 = T₁₈₉ + T₁₉₀ + ... + T₂₅₄.

It can be written as a sum of positive squares in 2 ways, for example, as 1258884 + 379456 = 1122^2 + 616^2 .

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (1638347) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2082 + ... + 2758.

It is an arithmetic number, because the mean of its divisors is an integer number (105203).

2^1638340 is an apocalyptic number.

1638340 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 1638340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1893654).

1638340 is an abundant number, since it is smaller than the sum of its proper divisors (2148968).

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

1638340 is a wasteful number, since it uses less digits than its factorization.

1638340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 708 (or 695 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 1638340 is about 1279.9765622854. The cubic root of 1638340 is about 117.8875688641.

The spelling of 1638340 in words is "one million, six hundred thirty-eight thousand, three hundred forty".