21535123 has 2 divisors, whose sum is σ = 21535124. Its totient is φ = 21535122.

The previous prime is 21535121. The next prime is 21535169. The reversal of 21535123 is 32153512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21535123 - 2¹ = 21535121 is a prime.

Together with 21535121, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21535094 and 21535103.

It is not a weakly prime, because it can be changed into another prime (21535121) 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 as a sum of consecutive naturals, namely, 10767561 + 10767562.

It is an arithmetic number, because the mean of its divisors is an integer number (10767562).

Almost surely, 2^21535123 is an apocalyptic number.

21535123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21535123 is an equidigital number, since it uses as much as digits as its factorization.

21535123 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 900, while the sum is 22.

The square root of 21535123 is about 4640.5951126984. The cubic root of 21535123 is about 278.2162241343.

Adding to 21535123 its reverse (32153512), we get a palindrome (53688635).

The spelling of 21535123 in words is "twenty-one million, five hundred thirty-five thousand, one hundred twenty-three".