2643745985 has 4 divisors (see below), whose sum is σ = 3172495188. Its totient is φ = 2114996784.

The previous prime is 2643745967. The next prime is 2643745987. The reversal of 2643745985 is 5895473462.

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 296149681 + 2347596304 = 17209^2 + 48452^2 .

It is a cyclic number.

It is not a de Polignac number, because 2643745985 - 2⁶ = 2643745921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2643745987) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 264374594 + ... + 264374603.

It is an arithmetic number, because the mean of its divisors is an integer number (793123797).

Almost surely, 2^2643745985 is an apocalyptic number.

It is an amenable number.

2643745985 is a deficient number, since it is larger than the sum of its proper divisors (528749203).

2643745985 is an equidigital number, since it uses as much as digits as its factorization.

2643745985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 528749202.

The product of its digits is 7257600, while the sum is 53.

The square root of 2643745985 is about 51417.3704597969. The cubic root of 2643745985 is about 1382.7380325613.

The spelling of 2643745985 in words is "two billion, six hundred forty-three million, seven hundred forty-five thousand, nine hundred eighty-five".