66405505438 has 32 divisors (see below), whose sum is σ = 105181021440. Its totient is φ = 31356331200.

The previous prime is 66405505403. The next prime is 66405505613. The reversal of 66405505438 is 83450550466.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26850970 + ... + 26853442.

It is an arithmetic number, because the mean of its divisors is an integer number (3286906920).

Almost surely, 2^66405505438 is an apocalyptic number.

66405505438 is a deficient number, since it is larger than the sum of its proper divisors (38775516002).

66405505438 is a wasteful number, since it uses less digits than its factorization.

66405505438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4432.

The product of its (nonzero) digits is 1728000, while the sum is 46.

It can be divided in two parts, 66 and 405505438, that added together give a palindrome (405505504).

The spelling of 66405505438 in words is "sixty-six billion, four hundred five million, five hundred five thousand, four hundred thirty-eight".