21360521 has 12 divisors (see below), whose sum is σ = 26760132. Its totient is φ = 16900128.

The previous prime is 21360487. The next prime is 21360523. The reversal of 21360521 is 12506312.

It can be written as a sum of positive squares in 2 ways, for example, as 9834496 + 11526025 = 3136^2 + 3395^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21360521 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21360493 and 21360502.

It is not an unprimeable number, because it can be changed into a prime (21360523) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16130 + ... + 17403.

It is an arithmetic number, because the mean of its divisors is an integer number (2230011).

Almost surely, 2^21360521 is an apocalyptic number.

It is an amenable number.

21360521 is a deficient number, since it is larger than the sum of its proper divisors (5399611).

21360521 is a wasteful number, since it uses less digits than its factorization.

21360521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33560 (or 33553 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21360521 is about 4621.7443676603. The cubic root of 21360521 is about 277.4622776958.

Adding to 21360521 its reverse (12506312), we get a palindrome (33866833).

The spelling of 21360521 in words is "twenty-one million, three hundred sixty thousand, five hundred twenty-one".