21533107 has 4 divisors (see below), whose sum is σ = 21561256. Its totient is φ = 21504960.

The previous prime is 21533047. The next prime is 21533111. The reversal of 21533107 is 70133512.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21533107 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21533117) 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, 12894 + ... + 14467.

It is an arithmetic number, because the mean of its divisors is an integer number (5390314).

Almost surely, 2^21533107 is an apocalyptic number.

21533107 is a deficient number, since it is larger than the sum of its proper divisors (28149).

21533107 is an equidigital number, since it uses as much as digits as its factorization.

21533107 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28148.

The product of its (nonzero) digits is 630, while the sum is 22.

The square root of 21533107 is about 4640.3778940944. The cubic root of 21533107 is about 278.2075421715.

Adding to 21533107 its reverse (70133512), we get a palindrome (91666619).

The spelling of 21533107 in words is "twenty-one million, five hundred thirty-three thousand, one hundred seven".