2168966821 has 6 divisors (see below), whose sum is σ = 2523083910. Its totient is φ = 1859114376.

The previous prime is 2168966809. The next prime is 2168966843. The reversal of 2168966821 is 1286698612.

It can be written as a sum of positive squares in only one way, i.e., 2133146596 + 35820225 = 46186^2 + 5985^2 .

It is not a de Polignac number, because 2168966821 - 2¹⁹ = 2168442533 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49), and also a Moran number because the ratio is a prime number: 44264629 = 2168966821 / (2 + 1 + 6 + 8 + 9 + 6 + 6 + 8 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2168966321) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 22132266 + ... + 22132363.

It is an arithmetic number, because the mean of its divisors is an integer number (420513985).

Almost surely, 2^2168966821 is an apocalyptic number.

It is an amenable number.

2168966821 is a deficient number, since it is larger than the sum of its proper divisors (354117089).

2168966821 is an equidigital number, since it uses as much as digits as its factorization.

2168966821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44264643 (or 44264636 counting only the distinct ones).

The product of its digits is 497664, while the sum is 49.

The square root of 2168966821 is about 46572.1678795394. The cubic root of 2168966821 is about 1294.4470880437.

Subtracting from 2168966821 its reverse (1286698612), we obtain a square (882268209 = 29703²).

The spelling of 2168966821 in words is "two billion, one hundred sixty-eight million, nine hundred sixty-six thousand, eight hundred twenty-one".