634640 has 20 divisors (see below), whose sum is σ = 1475724. Its totient is φ = 253824.

The previous prime is 634609. The next prime is 634643. The reversal of 634640 is 46436.

It can be written as a sum of positive squares in 2 ways, for example, as 204304 + 430336 = 452^2 + 656^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is not an unprimeable number, because it can be changed into a prime (634643) by changing a digit.

634640 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, 3887 + ... + 4046.

2⁶³⁴⁶⁴⁰ is an apocalyptic number.

It is an amenable number.

634640 is an abundant number, since it is smaller than the sum of its proper divisors (841084).

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

634640 is a wasteful number, since it uses less digits than its factorization.

634640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7946 (or 7940 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 634640 is about 796.6429564115. The cubic root of 634640 is about 85.9361343034.

The spelling of 634640 in words is "six hundred thirty-four thousand, six hundred forty".