213878809 has 2 divisors, whose sum is σ = 213878810. Its totient is φ = 213878808.

The previous prime is 213878803. The next prime is 213878849. The reversal of 213878809 is 908878312.

213878809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 194518809 + 19360000 = 13947^2 + 4400^2 .

It is a cyclic number.

It is not a de Polignac number, because 213878809 - 2⁷ = 213878681 is a prime.

It is not a weakly prime, because it can be changed into another prime (213878803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106939404 + 106939405.

It is an arithmetic number, because the mean of its divisors is an integer number (106939405).

Almost surely, 2^213878809 is an apocalyptic number.

It is an amenable number.

213878809 is a deficient number, since it is larger than the sum of its proper divisors (1).

213878809 is an equidigital number, since it uses as much as digits as its factorization.

213878809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 193536, while the sum is 46.

The square root of 213878809 is about 14624.5960286088. The cubic root of 213878809 is about 598.0294696946.

The spelling of 213878809 in words is "two hundred thirteen million, eight hundred seventy-eight thousand, eight hundred nine".