1381778 has 4 divisors (see below), whose sum is σ = 2072670. Its totient is φ = 690888.

The previous prime is 1381769. The next prime is 1381819. The reversal of 1381778 is 8771831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8771831 = 331 ⋅26501.

It can be written as a sum of positive squares in only one way, i.e., 1006009 + 375769 = 1003^2 + 613^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345443 + ... + 345446.

2^1381778 is an apocalyptic number.

1381778 is a deficient number, since it is larger than the sum of its proper divisors (690892).

1381778 is an equidigital number, since it uses as much as digits as its factorization.

1381778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 690891.

The product of its digits is 9408, while the sum is 35.

The square root of 1381778 is about 1175.4905359041. The cubic root of 1381778 is about 111.3814219293.

The spelling of 1381778 in words is "one million, three hundred eighty-one thousand, seven hundred seventy-eight".