6640811545 has 16 divisors (see below), whose sum is σ = 8043022800. Its totient is φ = 5263467264.

The previous prime is 6640811539. The next prime is 6640811563. The reversal of 6640811545 is 5451180466.

It can be written as a sum of positive squares in 8 ways, for example, as 1148667664 + 5492143881 = 33892^2 + 74109^2 .

It is a cyclic number.

It is not a de Polignac number, because 6640811545 - 2⁷ = 6640811417 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6640811498 and 6640811507.

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, 284539 + ... + 306991.

It is an arithmetic number, because the mean of its divisors is an integer number (502688925).

Almost surely, 2^6640811545 is an apocalyptic number.

It is an amenable number.

6640811545 is a deficient number, since it is larger than the sum of its proper divisors (1402211255).

6640811545 is a wasteful number, since it uses less digits than its factorization.

6640811545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23004.

The product of its (nonzero) digits is 115200, while the sum is 40.

The square root of 6640811545 is about 81491.1746448657. The cubic root of 6640811545 is about 1879.6358455123.

The spelling of 6640811545 in words is "six billion, six hundred forty million, eight hundred eleven thousand, five hundred forty-five".