1781369 has 2 divisors, whose sum is σ = 1781370. Its totient is φ = 1781368.

The previous prime is 1781363. The next prime is 1781393. The reversal of 1781369 is 9631871.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1721344 + 60025 = 1312^2 + 245^2 .

It is a cyclic number.

It is not a de Polignac number, because 1781369 - 2⁸ = 1781113 is a prime.

It is a super-2 number, since 2×1781369² = 6346551028322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1781363) 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 as a sum of consecutive naturals, namely, 890684 + 890685.

It is an arithmetic number, because the mean of its divisors is an integer number (890685).

2^1781369 is an apocalyptic number.

It is an amenable number.

1781369 is a deficient number, since it is larger than the sum of its proper divisors (1).

1781369 is an equidigital number, since it uses as much as digits as its factorization.

1781369 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9072, while the sum is 35.

The square root of 1781369 is about 1334.6793622440. The cubic root of 1781369 is about 121.2228890390. Note that the first 3 decimals are identical.

The spelling of 1781369 in words is "one million, seven hundred eighty-one thousand, three hundred sixty-nine".