208427858521 has 3 divisors (see below), whose sum is σ = 208428315061. Its totient is φ = 208427401982.

The previous prime is 208427858447. The next prime is 208427858531. The reversal of 208427858521 is 125858724802.

It is a happy number.

The square root of 208427858521 is 456539.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 125858724802 = 2 ⋅62929362401.

It is a de Polignac number, because none of the positive numbers 2^k-208427858521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (208427858531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 228270 + ... + 684808.

Almost surely, 2^208427858521 is an apocalyptic number.

208427858521 is the 456539-th square number.

208427858521 is the 228270-th centered octagonal number.

It is an amenable number.

208427858521 is a deficient number, since it is larger than the sum of its proper divisors (456540).

208427858521 is an frugal number, since it uses more digits than its factorization.

208427858521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 913078 (or 456539 counting only the distinct ones).

The product of its (nonzero) digits is 2867200, while the sum is 52.

The spelling of 208427858521 in words is "two hundred eight billion, four hundred twenty-seven million, eight hundred fifty-eight thousand, five hundred twenty-one".