635861 has 4 divisors (see below), whose sum is σ = 640224. Its totient is φ = 631500.

The previous prime is 635849. The next prime is 635867. The reversal of 635861 is 168536.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 635861 - 2¹⁴ = 619477 is a prime.

It is a super-2 number, since 2×635861² = 808638422642, which contains 22 as substring.

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 635861.

It is not an unprimeable number, because it can be changed into a prime (635867) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1955 + ... + 2256.

It is an arithmetic number, because the mean of its divisors is an integer number (160056).

2⁶³⁵⁸⁶¹ is an apocalyptic number.

It is an amenable number.

635861 is a deficient number, since it is larger than the sum of its proper divisors (4363).

635861 is a wasteful number, since it uses less digits than its factorization.

635861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4362.

The product of its digits is 4320, while the sum is 29.

The square root of 635861 is about 797.4089289693. The cubic root of 635861 is about 85.9912105674.

The spelling of 635861 in words is "six hundred thirty-five thousand, eight hundred sixty-one".