634721 has 8 divisors (see below), whose sum is σ = 660744. Its totient is φ = 609280.

The previous prime is 634717. The next prime is 634727. The reversal of 634721 is 127436.

It can be written as a sum of positive squares in 4 ways, for example, as 18496 + 616225 = 136^2 + 785^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 634721 - 2² = 634717 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 634721.

It is not an unprimeable number, because it can be changed into a prime (634727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4565 + ... + 4701.

It is an arithmetic number, because the mean of its divisors is an integer number (82593).

2⁶³⁴⁷²¹ is an apocalyptic number.

It is an amenable number.

634721 is a deficient number, since it is larger than the sum of its proper divisors (26023).

634721 is a wasteful number, since it uses less digits than its factorization.

634721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 291.

The product of its digits is 1008, while the sum is 23.

The square root of 634721 is about 796.6937931226. The cubic root of 634721 is about 85.9397901979.

The spelling of 634721 in words is "six hundred thirty-four thousand, seven hundred twenty-one".