634 has 4 divisors (see below), whose sum is σ = 954. Its totient is φ = 316.

The previous prime is 631. The next prime is 641. The reversal of 634 is 436.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 625 + 9 = 25^2 + 3^2 .

It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an alternating number because its digits alternate between even and odd.

It is a plaindrome in base 12, base 13, base 14 and base 16.

It is a nialpdrome in base 9.

It is not an unprimeable number, because it can be changed into a prime (631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 157 + ... + 160.

634 is a deficient number, since it is larger than the sum of its proper divisors (320).

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

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

The sum of its prime factors is 319.

The product of its digits is 72, while the sum is 13.

The square root of 634 is about 25.1793566240. The cubic root of 634 is about 8.5907237278.

It can be divided in two parts, 63 and 4, that multiplied together give a palindrome (252).

The spelling of 634 in words is "six hundred thirty-four", and thus it is an aban number.