208564921 has 4 divisors (see below), whose sum is σ = 213415312. Its totient is φ = 203714532.

The previous prime is 208564907. The next prime is 208564927. The reversal of 208564921 is 129465802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 208564921 - 2¹⁵ = 208532153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (208564927) 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, 2425131 + ... + 2425216.

It is an arithmetic number, because the mean of its divisors is an integer number (53353828).

Almost surely, 2^208564921 is an apocalyptic number.

It is an amenable number.

208564921 is a deficient number, since it is larger than the sum of its proper divisors (4850391).

208564921 is an equidigital number, since it uses as much as digits as its factorization.

208564921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4850390.

The product of its (nonzero) digits is 34560, while the sum is 37.

The square root of 208564921 is about 14441.7769336048. The cubic root of 208564921 is about 593.0351314372.

The spelling of 208564921 in words is "two hundred eight million, five hundred sixty-four thousand, nine hundred twenty-one".