66404651481 has 45 divisors (see below), whose sum is σ = 111961345119. Its totient is φ = 37923869088.

The previous prime is 66404651471. The next prime is 66404651513. The reversal of 66404651481 is 18415640466.

The square root of 66404651481 is 257691.

It is a perfect power (a square), and thus also a powerful number.

66404651481 is a `hidden beast` number, since 6 + 6 + 40 + 465 + 148 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1880523225 + 64524128256 = 43365^2 + 254016^2 .

It is not a de Polignac number, because 66404651481 - 2¹⁵ = 66404618713 is a prime.

It is a super-2 number, since 2×66404651481² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66404651471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 37879701 + ... + 37881453.

Almost surely, 2^66404651481 is an apocalyptic number.

66404651481 is the 257691-st square number.

66404651481 is the 128846-th centered octagonal number.

It is an amenable number.

66404651481 is a deficient number, since it is larger than the sum of its proper divisors (45556693638).

66404651481 is an frugal number, since it uses more digits than its factorization.

66404651481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3540 (or 1763 counting only the distinct ones).

The product of its (nonzero) digits is 552960, while the sum is 45.

The spelling of 66404651481 in words is "sixty-six billion, four hundred four million, six hundred fifty-one thousand, four hundred eighty-one".