21360385 has 16 divisors (see below), whose sum is σ = 27170640. Its totient is φ = 16092160.

The previous prime is 21360377. The next prime is 21360401. The reversal of 21360385 is 58306312.

It can be written as a sum of positive squares in 8 ways, for example, as 3779136 + 17581249 = 1944^2 + 4193^2 .

It is not a de Polignac number, because 21360385 - 2³ = 21360377 is a prime.

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, 4149 + ... + 7741.

It is an arithmetic number, because the mean of its divisors is an integer number (1698165).

Almost surely, 2^21360385 is an apocalyptic number.

It is an amenable number.

21360385 is a deficient number, since it is larger than the sum of its proper divisors (5810255).

21360385 is a wasteful number, since it uses less digits than its factorization.

21360385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3668.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21360385 is about 4621.7296545774. The cubic root of 21360385 is about 277.4616888376.

Adding to 21360385 its reverse (58306312), we get a palindrome (79666697).

The spelling of 21360385 in words is "twenty-one million, three hundred sixty thousand, three hundred eighty-five".