635721 has 12 divisors (see below), whose sum is σ = 896112. Its totient is φ = 400824.

The previous prime is 635711. The next prime is 635729. The reversal of 635721 is 127536.

635721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 635721 - 2⁵ = 635689 is a prime.

635721 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 635691 and 635700.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 635721.

It is not an unprimeable number, because it can be changed into a prime (635729) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 790 + ... + 1376.

It is an arithmetic number, because the mean of its divisors is an integer number (74676).

2⁶³⁵⁷²¹ is an apocalyptic number.

It is an amenable number.

635721 is a deficient number, since it is larger than the sum of its proper divisors (260391).

635721 is a wasteful number, since it uses less digits than its factorization.

635721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 628 (or 609 counting only the distinct ones).

The product of its digits is 1260, while the sum is 24.

The square root of 635721 is about 797.3211398176. The cubic root of 635721 is about 85.9848990973.

The spelling of 635721 in words is "six hundred thirty-five thousand, seven hundred twenty-one".