21516365 has 16 divisors (see below), whose sum is σ = 28401408. Its totient is φ = 15548736.

The previous prime is 21516359. The next prime is 21516403. The reversal of 21516365 is 56361512.

It is a cyclic number.

It is not a de Polignac number, because 21516365 - 2⁶ = 21516301 is a prime.

It is a Duffinian number.

It is a zygodrome in base 11.

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, 467 + ... + 6576.

It is an arithmetic number, because the mean of its divisors is an integer number (1775088).

Almost surely, 2^21516365 is an apocalyptic number.

It is an amenable number.

21516365 is a deficient number, since it is larger than the sum of its proper divisors (6885043).

21516365 is a wasteful number, since it uses less digits than its factorization.

21516365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7108.

The product of its digits is 5400, while the sum is 29.

The square root of 21516365 is about 4638.5735954062. The cubic root of 21516365 is about 278.1354213155.

Adding to 21516365 its reverse (56361512), we get a palindrome (77877877).

The spelling of 21516365 in words is "twenty-one million, five hundred sixteen thousand, three hundred sixty-five".