21905085 has 16 divisors (see below), whose sum is σ = 36572544. Its totient is φ = 11174592.

The previous prime is 21905083. The next prime is 21905089. The reversal of 21905085 is 58050912.

It is not a de Polignac number, because 21905085 - 2¹ = 21905083 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21905083) 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, 31402 + ... + 32091.

It is an arithmetic number, because the mean of its divisors is an integer number (2285784).

Almost surely, 2^21905085 is an apocalyptic number.

It is an amenable number.

21905085 is a deficient number, since it is larger than the sum of its proper divisors (14667459).

21905085 is a wasteful number, since it uses less digits than its factorization.

21905085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63524.

The product of its (nonzero) digits is 3600, while the sum is 30.

The square root of 21905085 is about 4680.2868501834. The cubic root of 21905085 is about 279.8003891947.

Adding to 21905085 its reverse (58050912), we get a palindrome (79955997).

The spelling of 21905085 in words is "twenty-one million, nine hundred five thousand, eighty-five".