636665540 has 48 divisors (see below), whose sum is σ = 1553067264. Its totient is φ = 214704000.

The previous prime is 636665501. The next prime is 636665543. The reversal of 636665540 is 45566636.

636665540 = T₃₄₉ + T₃₅₀ + ... + T₁₅₆₈.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (636665543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28736 + ... + 45815.

It is an arithmetic number, because the mean of its divisors is an integer number (32355568).

Almost surely, 2^636665540 is an apocalyptic number.

It is an amenable number.

636665540 is an abundant number, since it is smaller than the sum of its proper divisors (916401724).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

636665540 is a wasteful number, since it uses less digits than its factorization.

636665540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74628 (or 74626 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 41.

The square root of 636665540 is about 25232.2321644360. The cubic root of 636665540 is about 860.2746283549.

The spelling of 636665540 in words is "six hundred thirty-six million, six hundred sixty-five thousand, five hundred forty".