636043501660421 has 4 divisors (see below), whose sum is σ = 641672205215052. Its totient is φ = 630414798105792.

The previous prime is 636043501660361. The next prime is 636043501660451. The reversal of 636043501660421 is 124066105340636.

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 3819245495521 + 632224256164900 = 1954289^2 + 25144070^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-636043501660421 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 (636043501660451) 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, 2814351777146 + ... + 2814351777371.

It is an arithmetic number, because the mean of its divisors is an integer number (160418051303763).

Almost surely, 2^{636043501660421} is an apocalyptic number.

It is an amenable number.

636043501660421 is a deficient number, since it is larger than the sum of its proper divisors (5628703554631).

636043501660421 is a wasteful number, since it uses less digits than its factorization.

636043501660421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5628703554630.

The product of its (nonzero) digits is 1866240, while the sum is 47.

The spelling of 636043501660421 in words is "six hundred thirty-six trillion, forty-three billion, five hundred one million, six hundred sixty thousand, four hundred twenty-one".