2129208821 has 2 divisors, whose sum is σ = 2129208822. Its totient is φ = 2129208820.

The previous prime is 2129208791. The next prime is 2129208839. The reversal of 2129208821 is 1288029212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1316673796 + 812535025 = 36286^2 + 28505^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2129208821 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2129208841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1064604410 + 1064604411.

It is an arithmetic number, because the mean of its divisors is an integer number (1064604411).

Almost surely, 2^2129208821 is an apocalyptic number.

It is an amenable number.

2129208821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2129208821 is an equidigital number, since it uses as much as digits as its factorization.

2129208821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 35.

The square root of 2129208821 is about 46143.3507777665. The cubic root of 2129208821 is about 1286.4890248979.

The spelling of 2129208821 in words is "two billion, one hundred twenty-nine million, two hundred eight thousand, eight hundred twenty-one".