21500216 has 16 divisors (see below), whose sum is σ = 42066000. Its totient is φ = 10282624.

The previous prime is 21500209. The next prime is 21500231. The reversal of 21500216 is 61200512.

It is a junction number, because it is equal to n+sod(n) for n = 21500194 and 21500203.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58241 + ... + 58608.

It is an arithmetic number, because the mean of its divisors is an integer number (2629125).

Almost surely, 2^21500216 is an apocalyptic number.

It is an amenable number.

21500216 is a deficient number, since it is larger than the sum of its proper divisors (20565784).

21500216 is a wasteful number, since it uses less digits than its factorization.

21500216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116878 (or 116874 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21500216 is about 4636.8325395684. The cubic root of 21500216 is about 278.0658195170.

Adding to 21500216 its reverse (61200512), we get a palindrome (82700728).

The spelling of 21500216 in words is "twenty-one million, five hundred thousand, two hundred sixteen".