115809821 has 2 divisors, whose sum is σ = 115809822. Its totient is φ = 115809820.

The previous prime is 115809791. The next prime is 115809829. The reversal of 115809821 is 128908511.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58216900 + 57592921 = 7630^2 + 7589^2 .

It is an emirp because it is prime and its reverse (128908511) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 115809821 - 2²⁶ = 48700957 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (115809829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 57904910 + 57904911.

It is an arithmetic number, because the mean of its divisors is an integer number (57904911).

Almost surely, 2^115809821 is an apocalyptic number.

It is an amenable number.

115809821 is a deficient number, since it is larger than the sum of its proper divisors (1).

115809821 is an equidigital number, since it uses as much as digits as its factorization.

115809821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5760, while the sum is 35.

The square root of 115809821 is about 10761.4971542068. The cubic root of 115809821 is about 487.4332265327.

The spelling of 115809821 in words is "one hundred fifteen million, eight hundred nine thousand, eight hundred twenty-one".