844180821 has 18 divisors (see below), whose sum is σ = 1340303510. Its totient is φ = 511624080.

The previous prime is 844180801. The next prime is 844180823. The reversal of 844180821 is 128081448.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 471497796 + 372683025 = 21714^2 + 19305^2 .

It is not a de Polignac number, because 844180821 - 2¹¹ = 844178773 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (844180823) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 386506 + ... + 388683.

Almost surely, 2^844180821 is an apocalyptic number.

It is an amenable number.

844180821 is a deficient number, since it is larger than the sum of its proper divisors (496122689).

844180821 is a wasteful number, since it uses less digits than its factorization.

844180821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 775217 (or 775203 counting only the distinct ones).

The product of its (nonzero) digits is 16384, while the sum is 36.

The square root of 844180821 is about 29054.7899837531. The cubic root of 844180821 is about 945.1015898175.

The spelling of 844180821 in words is "eight hundred forty-four million, one hundred eighty thousand, eight hundred twenty-one".