1687644 has 72 divisors (see below), whose sum is σ = 5034848. Its totient is φ = 466560.

The previous prime is 1687643. The next prime is 1687657. The reversal of 1687644 is 4467861.

1687644 is a `hidden beast` number, since 1 + 6 + 8 + 7 + 644 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1687599 and 1687608.

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 23 ways as a sum of consecutive naturals, for example, 9234 + ... + 9414.

2^1687644 is an apocalyptic number.

1687644 is a gapful number since it is divisible by the number (14) 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 1687644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2517424).

1687644 is an abundant number, since it is smaller than the sum of its proper divisors (3347204).

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

1687644 is a wasteful number, since it uses less digits than its factorization.

1687644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 235 (or 230 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 1687644 is about 1299.0935301201. The cubic root of 1687644 is about 119.0584652569.

The spelling of 1687644 in words is "one million, six hundred eighty-seven thousand, six hundred forty-four".