1687640 has 32 divisors (see below), whose sum is σ = 3922560. Its totient is φ = 652800.

The previous prime is 1687633. The next prime is 1687643. The reversal of 1687640 is 467861.

It is a junction number, because it is equal to n+sod(n) for n = 1687597 and 1687606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1687643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 560 + ... + 1920.

It is an arithmetic number, because the mean of its divisors is an integer number (122580).

2^1687640 is an apocalyptic number.

1687640 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 1687640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1961280).

1687640 is an abundant number, since it is smaller than the sum of its proper divisors (2234920).

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

1687640 is a wasteful number, since it uses less digits than its factorization.

1687640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1403 (or 1399 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 1687640 is about 1299.0919905842. The cubic root of 1687640 is about 119.0583711939.

The spelling of 1687640 in words is "one million, six hundred eighty-seven thousand, six hundred forty".