1981165 has 8 divisors (see below), whose sum is σ = 2441880. Its totient is φ = 1541952.

The previous prime is 1981159. The next prime is 1981169. The reversal of 1981165 is 5611891.

It can be written as a sum of positive squares in 4 ways, for example, as 1108809 + 872356 = 1053^2 + 934^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1981165 - 2⁷ = 1981037 is a prime.

1981165 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981169) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5170 + ... + 5539.

It is an arithmetic number, because the mean of its divisors is an integer number (305235).

2^1981165 is an apocalyptic number.

It is an amenable number.

1981165 is a deficient number, since it is larger than the sum of its proper divisors (460715).

1981165 is a wasteful number, since it uses less digits than its factorization.

1981165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10751.

The product of its digits is 2160, while the sum is 31.

The square root of 1981165 is about 1407.5386317967. The cubic root of 1981165 is about 125.5953466638.

The spelling of 1981165 in words is "one million, nine hundred eighty-one thousand, one hundred sixty-five".