1965981805 has 4 divisors (see below), whose sum is σ = 2359178172. Its totient is φ = 1572785440.

The previous prime is 1965981799. The next prime is 1965981821. The reversal of 1965981805 is 5081895691.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5081895691 = 1549 ⋅3280759.

It can be written as a sum of positive squares in 2 ways, for example, as 320624836 + 1645356969 = 17906^2 + 40563^2 .

It is not a de Polignac number, because 1965981805 - 2²¹ = 1963884653 is a prime.

It is a Duffinian number.

It is a congruent 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, 196598176 + ... + 196598185.

It is an arithmetic number, because the mean of its divisors is an integer number (589794543).

Almost surely, 2^1965981805 is an apocalyptic number.

It is an amenable number.

1965981805 is a deficient number, since it is larger than the sum of its proper divisors (393196367).

1965981805 is an equidigital number, since it uses as much as digits as its factorization.

1965981805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 393196366.

The product of its (nonzero) digits is 777600, while the sum is 52.

The square root of 1965981805 is about 44339.3933765450. The cubic root of 1965981805 is about 1252.7367886838.

The spelling of 1965981805 in words is "one billion, nine hundred sixty-five million, nine hundred eighty-one thousand, eight hundred five".