208153661 has 4 divisors (see below), whose sum is σ = 220398012. Its totient is φ = 195909312.

The previous prime is 208153639. The next prime is 208153663. The reversal of 208153661 is 166351802.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 152053561 + 56100100 = 12331^2 + 7490^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-208153661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (208153663) 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 in 3 ways as a sum of consecutive naturals, for example, 6122150 + ... + 6122183.

It is an arithmetic number, because the mean of its divisors is an integer number (55099503).

Almost surely, 2^208153661 is an apocalyptic number.

It is an amenable number.

208153661 is a deficient number, since it is larger than the sum of its proper divisors (12244351).

208153661 is a wasteful number, since it uses less digits than its factorization.

208153661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12244350.

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 208153661 is about 14427.5313550170. The cubic root of 208153661 is about 592.6450816480.

The spelling of 208153661 in words is "two hundred eight million, one hundred fifty-three thousand, six hundred sixty-one".