21435523 has 4 divisors (see below), whose sum is σ = 21512088. Its totient is φ = 21358960.

The previous prime is 21435509. The next prime is 21435527. The reversal of 21435523 is 32553412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21435523 - 2¹³ = 21427331 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21435527) 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, 37861 + ... + 38422.

It is an arithmetic number, because the mean of its divisors is an integer number (5378022).

Almost surely, 2^21435523 is an apocalyptic number.

21435523 is a deficient number, since it is larger than the sum of its proper divisors (76565).

21435523 is an equidigital number, since it uses as much as digits as its factorization.

21435523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76564.

The product of its digits is 3600, while the sum is 25.

The square root of 21435523 is about 4629.8512935082. The cubic root of 21435523 is about 277.7866442622.

Adding to 21435523 its reverse (32553412), we get a palindrome (53988935).

The spelling of 21435523 in words is "twenty-one million, four hundred thirty-five thousand, five hundred twenty-three".