1778881 has 8 divisors (see below), whose sum is σ = 1928360. Its totient is φ = 1631232.

The previous prime is 1778879. The next prime is 1778899. The reversal of 1778881 is 1888771.

It is the 545-th star number.

It can be written as a sum of positive squares in 4 ways, for example, as 36481 + 1742400 = 191^2 + 1320^2 .

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 1778881 - 2¹ = 1778879 is a prime.

It is a super-2 number, since 2×1778881² = 6328835224322, which contains 22 as substring.

It is a Duffinian number.

It is a zygodrome in base 9.

It is not an unprimeable number, because it can be changed into a prime (1778801) 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, 2155 + ... + 2863.

It is an arithmetic number, because the mean of its divisors is an integer number (241045).

2^1778881 is an apocalyptic number.

It is an amenable number.

1778881 is a deficient number, since it is larger than the sum of its proper divisors (149479).

1778881 is a wasteful number, since it uses less digits than its factorization.

1778881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 915.

The product of its digits is 25088, while the sum is 40.

The square root of 1778881 is about 1333.7469775036. The cubic root of 1778881 is about 121.1664262715.

The spelling of 1778881 in words is "one million, seven hundred seventy-eight thousand, eight hundred eighty-one".