1681836749 has 4 divisors (see below), whose sum is σ = 1698488700. Its totient is φ = 1665184800.

The previous prime is 1681836733. The next prime is 1681836781. The reversal of 1681836749 is 9476381861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9476381861 = 9473 ⋅1000357.

It can be written as a sum of positive squares in 2 ways, for example, as 976562500 + 705274249 = 31250^2 + 26557^2 .

It is a cyclic number.

It is not a de Polignac number, because 1681836749 - 2⁴ = 1681836733 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1681836749.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1681836799) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8325824 + ... + 8326025.

It is an arithmetic number, because the mean of its divisors is an integer number (424622175).

Almost surely, 2^1681836749 is an apocalyptic number.

It is an amenable number.

1681836749 is a deficient number, since it is larger than the sum of its proper divisors (16651951).

1681836749 is a wasteful number, since it uses less digits than its factorization.

1681836749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16651950.

The product of its digits is 1741824, while the sum is 53.

The square root of 1681836749 is about 41010.2029865740. The cubic root of 1681836749 is about 1189.2174666006.

The spelling of 1681836749 in words is "one billion, six hundred eighty-one million, eight hundred thirty-six thousand, seven hundred forty-nine".