2173821864 has 64 divisors (see below), whose sum is σ = 5532770880. Its totient is φ = 711552000.

The previous prime is 2173821851. The next prime is 2173821869. The reversal of 2173821864 is 4681283712.

It is not an unprimeable number, because it can be changed into a prime (2173821869) 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, 1596544 + ... + 1597904.

It is an arithmetic number, because the mean of its divisors is an integer number (86449545).

Almost surely, 2^2173821864 is an apocalyptic number.

2173821864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2173821864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2766385440).

2173821864 is an abundant number, since it is smaller than the sum of its proper divisors (3358949016).

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

2173821864 is a wasteful number, since it uses less digits than its factorization.

2173821864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2522 (or 2518 counting only the distinct ones).

The product of its digits is 129024, while the sum is 42.

The square root of 2173821864 is about 46624.2626107910. The cubic root of 2173821864 is about 1295.4122039170.

The spelling of 2173821864 in words is "two billion, one hundred seventy-three million, eight hundred twenty-one thousand, eight hundred sixty-four".