690640 has 40 divisors (see below), whose sum is σ = 1640520. Its totient is φ = 270336.

The previous prime is 690629. The next prime is 690661. The reversal of 690640 is 46096.

It can be written as a sum of positive squares in 4 ways, for example, as 11664 + 678976 = 108^2 + 824^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7072 + ... + 7168.

It is an arithmetic number, because the mean of its divisors is an integer number (41013).

2⁶⁹⁰⁶⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 690640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (820260).

690640 is an abundant number, since it is smaller than the sum of its proper divisors (949880).

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

690640 is a wasteful number, since it uses less digits than its factorization.

690640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199 (or 193 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 690640 is about 831.0475317333. The cubic root of 690640 is about 88.3928715340.

The spelling of 690640 in words is "six hundred ninety thousand, six hundred forty".