21524539 has 2 divisors, whose sum is σ = 21524540. Its totient is φ = 21524538.

The previous prime is 21524513. The next prime is 21524593. The reversal of 21524539 is 93542512.

Together with next prime (21524593) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21524539 - 2¹¹ = 21522491 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21524539.

It is not a weakly prime, because it can be changed into another prime (21524939) 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, 10762269 + 10762270.

It is an arithmetic number, because the mean of its divisors is an integer number (10762270).

Almost surely, 2^21524539 is an apocalyptic number.

21524539 is a deficient number, since it is larger than the sum of its proper divisors (1).

21524539 is an equidigital number, since it uses as much as digits as its factorization.

21524539 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10800, while the sum is 31.

The square root of 21524539 is about 4639.4546015669. The cubic root of 21524539 is about 278.1706377829.

The spelling of 21524539 in words is "twenty-one million, five hundred twenty-four thousand, five hundred thirty-nine".