821091765875 has 8 divisors (see below), whose sum is σ = 1024722523968. Its totient is φ = 656873412600.

The previous prime is 821091765859. The next prime is 821091765877. The reversal of 821091765875 is 578567190128.

It is not a de Polignac number, because 821091765875 - 2⁴ = 821091765859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821091765877) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3284366939 + ... + 3284367188.

It is an arithmetic number, because the mean of its divisors is an integer number (128090315496).

Almost surely, 2^821091765875 is an apocalyptic number.

821091765875 is a deficient number, since it is larger than the sum of its proper divisors (203630758093).

821091765875 is an equidigital number, since it uses as much as digits as its factorization.

821091765875 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6568734142 (or 6568734132 counting only the distinct ones).

The product of its (nonzero) digits is 8467200, while the sum is 59.

The spelling of 821091765875 in words is "eight hundred twenty-one billion, ninety-one million, seven hundred sixty-five thousand, eight hundred seventy-five".