1380781 has 2 divisors, whose sum is σ = 1380782. Its totient is φ = 1380780.

The previous prime is 1380779. The next prime is 1380793. The reversal of 1380781 is 1870831.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1368900 + 11881 = 1170^2 + 109^2 .

It is a cyclic number.

It is not a de Polignac number, because 1380781 - 2¹ = 1380779 is a prime.

It is a super-2 number, since 2×1380781² = 3813112339922, which contains 22 as substring.

Together with 1380779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1380721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 690390 + 690391.

It is an arithmetic number, because the mean of its divisors is an integer number (690391).

2^1380781 is an apocalyptic number.

It is an amenable number.

1380781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1380781 is an equidigital number, since it uses as much as digits as its factorization.

1380781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1344, while the sum is 28.

The square root of 1380781 is about 1175.0663811036. The cubic root of 1380781 is about 111.3546269844.

The spelling of 1380781 in words is "one million, three hundred eighty thousand, seven hundred eighty-one".