21036523 has 4 divisors (see below), whose sum is σ = 21047040. Its totient is φ = 21026008.

The previous prime is 21036517. The next prime is 21036527. The reversal of 21036523 is 32563012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21036523 - 2¹³ = 21028331 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21036494 and 21036503.

It is not an unprimeable number, because it can be changed into a prime (21036527) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1228 + ... + 6601.

It is an arithmetic number, because the mean of its divisors is an integer number (5261760).

Almost surely, 2^21036523 is an apocalyptic number.

21036523 is a deficient number, since it is larger than the sum of its proper divisors (10517).

21036523 is an equidigital number, since it uses as much as digits as its factorization.

21036523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10516.

The product of its (nonzero) digits is 1080, while the sum is 22.

The square root of 21036523 is about 4586.5589498010. The cubic root of 21036523 is about 276.0522681588.

Adding to 21036523 its reverse (32563012), we get a palindrome (53599535).

The spelling of 21036523 in words is "twenty-one million, thirty-six thousand, five hundred twenty-three".