117809821 has 2 divisors, whose sum is σ = 117809822. Its totient is φ = 117809820.

The previous prime is 117809819. The next prime is 117809869. The reversal of 117809821 is 128908711.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 89984196 + 27825625 = 9486^2 + 5275^2 .

It is a cyclic number.

It is not a de Polignac number, because 117809821 - 2¹ = 117809819 is a prime.

Together with 117809819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (117809891) 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 as a sum of consecutive naturals, namely, 58904910 + 58904911.

It is an arithmetic number, because the mean of its divisors is an integer number (58904911).

Almost surely, 2^117809821 is an apocalyptic number.

It is an amenable number.

117809821 is a deficient number, since it is larger than the sum of its proper divisors (1).

117809821 is an equidigital number, since it uses as much as digits as its factorization.

117809821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8064, while the sum is 37.

The square root of 117809821 is about 10854.0232632881. The cubic root of 117809821 is about 490.2231678151.

The spelling of 117809821 in words is "one hundred seventeen million, eight hundred nine thousand, eight hundred twenty-one".