691648 has 28 divisors (see below), whose sum is σ = 1399032. Its totient is φ = 339200.

The previous prime is 691637. The next prime is 691651. The reversal of 691648 is 846196.

It is a congruent number.

It is an unprimeable number.

691648 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6411 + ... + 6517.

2⁶⁹¹⁶⁴⁸ 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 691648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (699516).

691648 is an abundant number, since it is smaller than the sum of its proper divisors (707384).

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

691648 is a wasteful number, since it uses less digits than its factorization.

691648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220 (or 210 counting only the distinct ones).

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

The square root of 691648 is about 831.6537741152. The cubic root of 691648 is about 88.4358542273.

The spelling of 691648 in words is "six hundred ninety-one thousand, six hundred forty-eight".