2195810821 has 2 divisors, whose sum is σ = 2195810822. Its totient is φ = 2195810820.

The previous prime is 2195810789. The next prime is 2195810857. The reversal of 2195810821 is 1280185912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1136633796 + 1059177025 = 33714^2 + 32545^2 .

It is a cyclic number.

It is not a de Polignac number, because 2195810821 - 2⁵ = 2195810789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2195810891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1097905410 + 1097905411.

It is an arithmetic number, because the mean of its divisors is an integer number (1097905411).

Almost surely, 2^2195810821 is an apocalyptic number.

It is an amenable number.

2195810821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2195810821 is an equidigital number, since it uses as much as digits as its factorization.

2195810821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11520, while the sum is 37.

The square root of 2195810821 is about 46859.4795212239. The cubic root of 2195810821 is about 1299.7654055973.

The spelling of 2195810821 in words is "two billion, one hundred ninety-five million, eight hundred ten thousand, eight hundred twenty-one".