66440733121 has 27 divisors (see below), whose sum is σ = 80845155363. Its totient is φ = 54439123200.

The previous prime is 66440733119. The next prime is 66440733173. The reversal of 66440733121 is 12133704466.

The square root of 66440733121 is 257761.

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

It can be written as a sum of positive squares in only one way, i.e., 66274838721 + 165894400 = 257439^2 + 12880^2 .

It is not a de Polignac number, because 66440733121 - 2¹ = 66440733119 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66440733421) 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 26 ways as a sum of consecutive naturals, for example, 41498721 + ... + 41500321.

Almost surely, 2^66440733121 is an apocalyptic number.

66440733121 is the 257761-st square number.

66440733121 is the 128881-st centered octagonal number.

It is an amenable number.

66440733121 is a deficient number, since it is larger than the sum of its proper divisors (14404422242).

66440733121 is an frugal number, since it uses more digits than its factorization.

66440733121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3262 (or 1631 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 37.

The spelling of 66440733121 in words is "sixty-six billion, four hundred forty million, seven hundred thirty-three thousand, one hundred twenty-one".