636544081 has 4 divisors (see below), whose sum is σ = 636667632. Its totient is φ = 636420532.

The previous prime is 636544079. The next prime is 636544091. The reversal of 636544081 is 180445636.

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 636544081 - 2¹ = 636544079 is a prime.

It is a super-2 number, since 2×636544081² = 810376734112269122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 636544081.

It is not an unprimeable number, because it can be changed into a prime (636544091) 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, 53695 + ... + 64468.

It is an arithmetic number, because the mean of its divisors is an integer number (159166908).

Almost surely, 2^636544081 is an apocalyptic number.

It is an amenable number.

636544081 is a deficient number, since it is larger than the sum of its proper divisors (123551).

636544081 is a wasteful number, since it uses less digits than its factorization.

636544081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123550.

The product of its (nonzero) digits is 69120, while the sum is 37.

The square root of 636544081 is about 25229.8252272979. The cubic root of 636544081 is about 860.2199189694.

The spelling of 636544081 in words is "six hundred thirty-six million, five hundred forty-four thousand, eighty-one".