636256421 has 4 divisors (see below), whose sum is σ = 636388992. Its totient is φ = 636123852.

The previous prime is 636256391. The next prime is 636256447. The reversal of 636256421 is 124652636.

It is a happy number.

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 636256421 - 2¹⁰ = 636255397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636216421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58805 + ... + 68778.

It is an arithmetic number, because the mean of its divisors is an integer number (159097248).

Almost surely, 2^636256421 is an apocalyptic number.

It is an amenable number.

636256421 is a deficient number, since it is larger than the sum of its proper divisors (132571).

636256421 is a wasteful number, since it uses less digits than its factorization.

636256421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132570.

The product of its digits is 51840, while the sum is 35.

The square root of 636256421 is about 25224.1237905304. The cubic root of 636256421 is about 860.0903190701.

The spelling of 636256421 in words is "six hundred thirty-six million, two hundred fifty-six thousand, four hundred twenty-one".