844299800821 has 4 divisors (see below), whose sum is σ = 844303718700. Its totient is φ = 844295882944.

The previous prime is 844299800783. The next prime is 844299800887. The reversal of 844299800821 is 128008992448.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 529787458225 + 314512342596 = 727865^2 + 560814^2 .

It is a cyclic number.

It is not a de Polignac number, because 844299800821 - 2⁷ = 844299800693 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 (844299800891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1615636 + ... + 2073373.

It is an arithmetic number, because the mean of its divisors is an integer number (211075929675).

Almost surely, 2^844299800821 is an apocalyptic number.

It is an amenable number.

844299800821 is a deficient number, since it is larger than the sum of its proper divisors (3917879).

844299800821 is a wasteful number, since it uses less digits than its factorization.

844299800821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3917878.

The product of its (nonzero) digits is 2654208, while the sum is 55.

The spelling of 844299800821 in words is "eight hundred forty-four billion, two hundred ninety-nine million, eight hundred thousand, eight hundred twenty-one".