21500085 has 16 divisors (see below), whose sum is σ = 34594560. Its totient is φ = 11401920.

The previous prime is 21500069. The next prime is 21500111. The reversal of 21500085 is 58000512.

It is not a de Polignac number, because 21500085 - 2⁴ = 21500069 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1245 + ... + 6674.

It is an arithmetic number, because the mean of its divisors is an integer number (2162160).

Almost surely, 2^21500085 is an apocalyptic number.

It is an amenable number.

21500085 is a deficient number, since it is larger than the sum of its proper divisors (13094475).

21500085 is a wasteful number, since it uses less digits than its factorization.

21500085 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8108.

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 21500085 is about 4636.8184135245. The cubic root of 21500085 is about 278.0652547677.

Adding to 21500085 its reverse (58000512), we get a palindrome (79500597).

The spelling of 21500085 in words is "twenty-one million, five hundred thousand, eighty-five".