636621 has 4 divisors (see below), whose sum is σ = 848832. Its totient is φ = 424412.

The previous prime is 636619. The next prime is 636631. The reversal of 636621 is 126636.

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 636621 - 2¹ = 636619 is a prime.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 636591 and 636600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636631) 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, 106101 + ... + 106106.

It is an arithmetic number, because the mean of its divisors is an integer number (212208).

2⁶³⁶⁶²¹ is an apocalyptic number.

It is an amenable number.

636621 is a deficient number, since it is larger than the sum of its proper divisors (212211).

636621 is a wasteful number, since it uses less digits than its factorization.

636621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212210.

The product of its digits is 1296, while the sum is 24.

The square root of 636621 is about 797.8853301070. The cubic root of 636621 is about 86.0254566788.

The spelling of 636621 in words is "six hundred thirty-six thousand, six hundred twenty-one".