208991890 has 8 divisors (see below), whose sum is σ = 376185420. Its totient is φ = 83596752.

The previous prime is 208991857. The next prime is 208991891. The reversal of 208991890 is 98199802.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 201157489 + 7834401 = 14183^2 + 2799^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×208991890² = 87355220171544200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 208991890.

It is not an unprimeable number, because it can be changed into a prime (208991891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10449585 + ... + 10449604.

Almost surely, 2^208991890 is an apocalyptic number.

208991890 is a deficient number, since it is larger than the sum of its proper divisors (167193530).

208991890 is a wasteful number, since it uses less digits than its factorization.

208991890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20899196.

The product of its (nonzero) digits is 93312, while the sum is 46.

The square root of 208991890 is about 14456.5518018648. The cubic root of 208991890 is about 593.4395379329.

The spelling of 208991890 in words is "two hundred eight million, nine hundred ninety-one thousand, eight hundred ninety".