1640340 has 72 divisors (see below), whose sum is σ = 5366088. Its totient is φ = 403200.

The previous prime is 1640333. The next prime is 1640393. The reversal of 1640340 is 430461.

It can be written as a sum of positive squares in 4 ways, for example, as 171396 + 1468944 = 414^2 + 1212^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1990 + ... + 2690.

It is an arithmetic number, because the mean of its divisors is an integer number (74529).

2^1640340 is an apocalyptic number.

1640340 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 1640340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2683044).

1640340 is an abundant number, since it is smaller than the sum of its proper divisors (3725748).

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

1640340 is a wasteful number, since it uses less digits than its factorization.

1640340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 729 (or 724 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 1640340 is about 1280.7575883047. The cubic root of 1640340 is about 117.9355196888.

The spelling of 1640340 in words is "one million, six hundred forty thousand, three hundred forty".