821181673728 has 144 divisors (see below), whose sum is σ = 2615177322240. Its totient is φ = 252671256576.

The previous prime is 821181673723. The next prime is 821181673733. The reversal of 821181673728 is 827376181128.

821181673728 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (821181673723) and next prime (821181673733).

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (821181673723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4479576 + ... + 4659287.

Almost surely, 2^821181673728 is an apocalyptic number.

It is an amenable number.

821181673728 is an abundant number, since it is smaller than the sum of its proper divisors (1793995648512).

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

821181673728 is a wasteful number, since it uses less digits than its factorization.

821181673728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9138901 (or 9138881 counting only the distinct ones).

The product of its digits is 1806336, while the sum is 54.

The spelling of 821181673728 in words is "eight hundred twenty-one billion, one hundred eighty-one million, six hundred seventy-three thousand, seven hundred twenty-eight".