821234579891 has 16 divisors (see below), whose sum is σ = 936498278400. Its totient is φ = 713348251200.

The previous prime is 821234579887. The next prime is 821234579911. The reversal of 821234579891 is 198975432128.

It is a cyclic number.

It is not a de Polignac number, because 821234579891 - 2² = 821234579887 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 821234579891.

It is not an unprimeable number, because it can be changed into a prime (821234579821) 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, 15215546 + ... + 15269423.

It is an arithmetic number, because the mean of its divisors is an integer number (58531142400).

Almost surely, 2^821234579891 is an apocalyptic number.

821234579891 is a deficient number, since it is larger than the sum of its proper divisors (115263698509).

821234579891 is a wasteful number, since it uses less digits than its factorization.

821234579891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30485090.

The product of its digits is 8709120, while the sum is 59.

The spelling of 821234579891 in words is "eight hundred twenty-one billion, two hundred thirty-four million, five hundred seventy-nine thousand, eight hundred ninety-one".