636401 has 4 divisors (see below), whose sum is σ = 642804. Its totient is φ = 630000.

The previous prime is 636359. The next prime is 636403. The reversal of 636401 is 104636.

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

It can be written as a sum of positive squares in 2 ways, for example, as 524176 + 112225 = 724^2 + 335^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-636401 is a prime.

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 636401.

It is not an unprimeable number, because it can be changed into a prime (636403) 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, 3050 + ... + 3251.

It is an arithmetic number, because the mean of its divisors is an integer number (160701).

2⁶³⁶⁴⁰¹ is an apocalyptic number.

It is an amenable number.

636401 is a deficient number, since it is larger than the sum of its proper divisors (6403).

636401 is a wasteful number, since it uses less digits than its factorization.

636401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6402.

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 636401 is about 797.7474537722. The cubic root of 636401 is about 86.0155461349.

The spelling of 636401 in words is "six hundred thirty-six thousand, four hundred one".