6640457121 has 27 divisors (see below), whose sum is σ = 10035434227. Its totient is φ = 4230908880.

The previous prime is 6640457119. The next prime is 6640457141. The reversal of 6640457121 is 1217540466.

The square root of 6640457121 is 81489.

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

6640457121 is a `hidden beast` number, since 6 + 64 + 0 + 4 + 571 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 6090085521 + 550371600 = 78039^2 + 23460^2 .

It is not a de Polignac number, because 6640457121 - 2¹ = 6640457119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6640457141) 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, 5622151 + ... + 5623331.

Almost surely, 2^6640457121 is an apocalyptic number.

6640457121 is the 81489-th square number.

6640457121 is the 40745-th centered octagonal number.

It is an amenable number.

6640457121 is a deficient number, since it is larger than the sum of its proper divisors (3394977106).

6640457121 is an equidigital number, since it uses as much as digits as its factorization.

6640457121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2414 (or 1207 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The cubic root of 6640457121 is about 1879.6024058289.

Multiplying 6640457121 by its sum of digits (36), we get a square (239056456356 = 488934²).

Adding to 6640457121 its reverse (1217540466), we get a palindrome (7857997587).

It can be divided in two parts, 6640 and 457121, that added together give a square (463761 = 681²).

The spelling of 6640457121 in words is "six billion, six hundred forty million, four hundred fifty-seven thousand, one hundred twenty-one".