1378661 has 8 divisors (see below), whose sum is σ = 1421784. Its totient is φ = 1336320.

The previous prime is 1378639. The next prime is 1378669. The reversal of 1378661 is 1668731.

It can be written as a sum of positive squares in 4 ways, for example, as 12100 + 1366561 = 110^2 + 1169^2 .

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 1378661 - 2¹⁰ = 1377637 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1378669) 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, 5801 + ... + 6033.

It is an arithmetic number, because the mean of its divisors is an integer number (177723).

2^1378661 is an apocalyptic number.

It is an amenable number.

1378661 is a deficient number, since it is larger than the sum of its proper divisors (43123).

1378661 is an equidigital number, since it uses as much as digits as its factorization.

1378661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391.

The product of its digits is 6048, while the sum is 32.

The square root of 1378661 is about 1174.1639578866. The cubic root of 1378661 is about 111.2976078696.

The spelling of 1378661 in words is "one million, three hundred seventy-eight thousand, six hundred sixty-one".