21533045 has 4 divisors (see below), whose sum is σ = 25839660. Its totient is φ = 17226432.

The previous prime is 21533011. The next prime is 21533047. The reversal of 21533045 is 54033512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3775249 + 17757796 = 1943^2 + 4214^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21533045 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21533045.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2153300 + ... + 2153309.

It is an arithmetic number, because the mean of its divisors is an integer number (6459915).

Almost surely, 2^21533045 is an apocalyptic number.

It is an amenable number.

21533045 is a deficient number, since it is larger than the sum of its proper divisors (4306615).

21533045 is an equidigital number, since it uses as much as digits as its factorization.

21533045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4306614.

The product of its (nonzero) digits is 1800, while the sum is 23.

The square root of 21533045 is about 4640.3712135992. The cubic root of 21533045 is about 278.2072751581.

Adding to 21533045 its reverse (54033512), we get a palindrome (75566557).

The spelling of 21533045 in words is "twenty-one million, five hundred thirty-three thousand, forty-five".