1689640 has 32 divisors (see below), whose sum is σ = 3878280. Its totient is φ = 662272.

The previous prime is 1689617. The next prime is 1689641. The reversal of 1689640 is 469861.

It can be written as a sum of positive squares in 4 ways, for example, as 1483524 + 206116 = 1218^2 + 454^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1689596 and 1689605.

It is not an unprimeable number, because it can be changed into a prime (1689641) 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, 1722 + ... + 2518.

2^1689640 is an apocalyptic number.

1689640 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 1689640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1939140).

1689640 is an abundant number, since it is smaller than the sum of its proper divisors (2188640).

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

1689640 is a wasteful number, since it uses less digits than its factorization.

1689640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 861 (or 857 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 1689640 is about 1299.8615310871. The cubic root of 1689640 is about 119.1053841314.

The spelling of 1689640 in words is "one million, six hundred eighty-nine thousand, six hundred forty".