1645261165 has 4 divisors (see below), whose sum is σ = 1974313404. Its totient is φ = 1316208928.

The previous prime is 1645261159. The next prime is 1645261169. The reversal of 1645261165 is 5611625461.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 976625001 + 668636164 = 31251^2 + 25858^2 .

It is a cyclic number.

It is not a de Polignac number, because 1645261165 - 2⁵ = 1645261133 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645261169) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 164526112 + ... + 164526121.

It is an arithmetic number, because the mean of its divisors is an integer number (493578351).

Almost surely, 2^1645261165 is an apocalyptic number.

It is an amenable number.

1645261165 is a deficient number, since it is larger than the sum of its proper divisors (329052239).

1645261165 is an equidigital number, since it uses as much as digits as its factorization.

1645261165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329052238.

The product of its digits is 43200, while the sum is 37.

The square root of 1645261165 is about 40561.8190543767. The cubic root of 1645261165 is about 1180.5334093718.

The spelling of 1645261165 in words is "one billion, six hundred forty-five million, two hundred sixty-one thousand, one hundred sixty-five".