21533507 has 2 divisors, whose sum is σ = 21533508. Its totient is φ = 21533506.

The previous prime is 21533471. The next prime is 21533513. The reversal of 21533507 is 70533512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21533507 - 2⁶ = 21533443 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21533527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10766753 + 10766754.

It is an arithmetic number, because the mean of its divisors is an integer number (10766754).

Almost surely, 2^21533507 is an apocalyptic number.

21533507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21533507 is an equidigital number, since it uses as much as digits as its factorization.

21533507 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3150, while the sum is 26.

The square root of 21533507 is about 4640.4209938323. The cubic root of 21533507 is about 278.2092648263.

The spelling of 21533507 in words is "twenty-one million, five hundred thirty-three thousand, five hundred seven".