21535693 has 2 divisors, whose sum is σ = 21535694. Its totient is φ = 21535692.

The previous prime is 21535663. The next prime is 21535697. The reversal of 21535693 is 39653512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21511044 + 24649 = 4638^2 + 157^2 .

It is a cyclic number.

It is not a de Polignac number, because 21535693 - 2⁹ = 21535181 is a prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21535697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10767846 + 10767847.

It is an arithmetic number, because the mean of its divisors is an integer number (10767847).

Almost surely, 2^21535693 is an apocalyptic number.

It is an amenable number.

21535693 is a deficient number, since it is larger than the sum of its proper divisors (1).

21535693 is an equidigital number, since it uses as much as digits as its factorization.

21535693 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24300, while the sum is 34.

The square root of 21535693 is about 4640.6565268289. The cubic root of 21535693 is about 278.2186787577.

The spelling of 21535693 in words is "twenty-one million, five hundred thirty-five thousand, six hundred ninety-three".