1640445265 has 4 divisors (see below), whose sum is σ = 1968534324. Its totient is φ = 1312356208.

The previous prime is 1640445253. The next prime is 1640445281. The reversal of 1640445265 is 5625440461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5625440461 = 57041 ⋅98621.

It can be written as a sum of positive squares in 2 ways, for example, as 1041223824 + 599221441 = 32268^2 + 24479^2 .

It is a cyclic number.

It is not a de Polignac number, because 1640445265 - 2⁹ = 1640444753 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 164044522 + ... + 164044531.

It is an arithmetic number, because the mean of its divisors is an integer number (492133581).

Almost surely, 2^1640445265 is an apocalyptic number.

It is an amenable number.

1640445265 is a deficient number, since it is larger than the sum of its proper divisors (328089059).

1640445265 is an equidigital number, since it uses as much as digits as its factorization.

1640445265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328089058.

The product of its (nonzero) digits is 115200, while the sum is 37.

The square root of 1640445265 is about 40502.4106072713. The cubic root of 1640445265 is about 1179.3804238058.

The spelling of 1640445265 in words is "one billion, six hundred forty million, four hundred forty-five thousand, two hundred sixty-five".