21536533 has 16 divisors (see below), whose sum is σ = 23187456. Its totient is φ = 19958400.

The previous prime is 21536527. The next prime is 21536539. The reversal of 21536533 is 33563512.

It is an interprime number because it is at equal distance from previous prime (21536527) and next prime (21536539).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21536533 is a prime.

It is a Duffinian number.

Its product of digits (8100) is a multiple of the sum of its prime divisors (324).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21536539) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 169516 + ... + 169642.

It is an arithmetic number, because the mean of its divisors is an integer number (1449216).

Almost surely, 2^21536533 is an apocalyptic number.

21536533 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21536533 is a deficient number, since it is larger than the sum of its proper divisors (1650923).

21536533 is a wasteful number, since it uses less digits than its factorization.

21536533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324.

The product of its digits is 8100, while the sum is 28.

The square root of 21536533 is about 4640.7470303821. The cubic root of 21536533 is about 278.2222960185. Note that the first 4 decimals are identical.

The spelling of 21536533 in words is "twenty-one million, five hundred thirty-six thousand, five hundred thirty-three".