815221109 has 2 divisors, whose sum is σ = 815221110. Its totient is φ = 815221108.

The previous prime is 815221027. The next prime is 815221159. The reversal of 815221109 is 901122518.

815221109 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 756085009 + 59136100 = 27497^2 + 7690^2 .

It is a cyclic number.

It is not a de Polignac number, because 815221109 - 2⁸ = 815220853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (815221159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 407610554 + 407610555.

It is an arithmetic number, because the mean of its divisors is an integer number (407610555).

Almost surely, 2^815221109 is an apocalyptic number.

It is an amenable number.

815221109 is a deficient number, since it is larger than the sum of its proper divisors (1).

815221109 is an equidigital number, since it uses as much as digits as its factorization.

815221109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 29.

The square root of 815221109 is about 28552.0771398510. The cubic root of 815221109 is about 934.1683279160.

The spelling of 815221109 in words is "eight hundred fifteen million, two hundred twenty-one thousand, one hundred nine".