1681778426 has 24 divisors (see below), whose sum is σ = 2727412884. Its totient is φ = 777188160.

The previous prime is 1681778419. The next prime is 1681778437. The reversal of 1681778426 is 6248771861.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 1676493025 + 5285401 = 40945^2 + 2299^2 .

It is a Smith number, since the sum of its digits (50) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1196 + ... + 58008.

Almost surely, 2^1681778426 is an apocalyptic number.

1681778426 is a deficient number, since it is larger than the sum of its proper divisors (1045634458).

1681778426 is a wasteful number, since it uses less digits than its factorization.

1681778426 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56894 (or 56875 counting only the distinct ones).

The product of its digits is 903168, while the sum is 50.

The square root of 1681778426 is about 41009.4919012660. The cubic root of 1681778426 is about 1189.2037198181.

The spelling of 1681778426 in words is "one billion, six hundred eighty-one million, seven hundred seventy-eight thousand, four hundred twenty-six".