208020021 has 16 divisors (see below), whose sum is σ = 302818368. Its totient is φ = 125971200.

The previous prime is 208020011. The next prime is 208020049. The reversal of 208020021 is 120020802.

It is not a de Polignac number, because 208020021 - 2⁷ = 208019893 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (208020011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69855 + ... + 72771.

It is an arithmetic number, because the mean of its divisors is an integer number (18926148).

Almost surely, 2^208020021 is an apocalyptic number.

It is an amenable number.

208020021 is a deficient number, since it is larger than the sum of its proper divisors (94798347).

208020021 is a wasteful number, since it uses less digits than its factorization.

208020021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5092.

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 208020021 is about 14422.8991884434. The cubic root of 208020021 is about 592.5182233709.

Adding to 208020021 its reverse (120020802), we get a palindrome (328040823).

The spelling of 208020021 in words is "two hundred eight million, twenty thousand, twenty-one".