209135808 has 84 divisors (see below), whose sum is σ = 685098960. Its totient is φ = 59751936.

The previous prime is 209135777. The next prime is 209135813. The reversal of 209135808 is 808531902.

It is a tau number, because it is divible by the number of its divisors (84).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21903 + ... + 29966.

It is an arithmetic number, because the mean of its divisors is an integer number (8155940).

Almost surely, 2^209135808 is an apocalyptic number.

209135808 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

209135808 is an abundant number, since it is smaller than the sum of its proper divisors (475963152).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

209135808 is a wasteful number, since it uses less digits than its factorization.

209135808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51894 (or 51881 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 209135808 is about 14461.5285499148. The cubic root of 209135808 is about 593.5757266855.

The spelling of 209135808 in words is "two hundred nine million, one hundred thirty-five thousand, eight hundred eight".