21080205 has 24 divisors (see below), whose sum is σ = 37320192. Its totient is φ = 11002464.

The previous prime is 21080203. The next prime is 21080219. The reversal of 21080205 is 50208012.

It is not a de Polignac number, because 21080205 - 2¹ = 21080203 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21080201) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2869 + ... + 7098.

It is an arithmetic number, because the mean of its divisors is an integer number (1555008).

Almost surely, 2^21080205 is an apocalyptic number.

It is an amenable number.

21080205 is a deficient number, since it is larger than the sum of its proper divisors (16239987).

21080205 is a wasteful number, since it uses less digits than its factorization.

21080205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10025 (or 10022 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 21080205 is about 4591.3184380960. The cubic root of 21080205 is about 276.2432087491.

Adding to 21080205 its reverse (50208012), we get a palindrome (71288217).

The spelling of 21080205 in words is "twenty-one million, eighty thousand, two hundred five".