21533011 has 2 divisors, whose sum is σ = 21533012. Its totient is φ = 21533010.

The previous prime is 21533009. The next prime is 21533047. The reversal of 21533011 is 11033512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21533011 - 2¹ = 21533009 is a prime.

It is a super-2 number, since 2×21533011² = 927341125452242, which contains 22 as substring.

Together with 21533009, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21533111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10766505 + 10766506.

It is an arithmetic number, because the mean of its divisors is an integer number (10766506).

Almost surely, 2^21533011 is an apocalyptic number.

21533011 is a deficient number, since it is larger than the sum of its proper divisors (1).

21533011 is an equidigital number, since it uses as much as digits as its factorization.

21533011 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 90, while the sum is 16.

The square root of 21533011 is about 4640.3675500977. The cubic root of 21533011 is about 278.2071287312.

Adding to 21533011 its reverse (11033512), we get a palindrome (32566523).

The spelling of 21533011 in words is "twenty-one million, five hundred thirty-three thousand, eleven".