811721844 has 48 divisors (see below), whose sum is σ = 2109824640. Its totient is φ = 269884800.

The previous prime is 811721843. The next prime is 811721851. The reversal of 811721844 is 448127118.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 811721799 and 811721808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811721843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33937 + ... + 52679.

It is an arithmetic number, because the mean of its divisors is an integer number (43954680).

Almost surely, 2^811721844 is an apocalyptic number.

It is an amenable number.

811721844 is an abundant number, since it is smaller than the sum of its proper divisors (1298102796).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

811721844 is a wasteful number, since it uses less digits than its factorization.

811721844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19157 (or 19149 counting only the distinct ones).

The product of its digits is 14336, while the sum is 36.

The square root of 811721844 is about 28490.7325985135. The cubic root of 811721844 is about 932.8297990832.

The spelling of 811721844 in words is "eight hundred eleven million, seven hundred twenty-one thousand, eight hundred forty-four".