21524241821 has 2 divisors, whose sum is σ = 21524241822. Its totient is φ = 21524241820.

The previous prime is 21524241743. The next prime is 21524241829. The reversal of 21524241821 is 12814242512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19103109796 + 2421132025 = 138214^2 + 49205^2 .

It is a cyclic number.

It is not a de Polignac number, because 21524241821 - 2²² = 21520047517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21524241829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10762120910 + 10762120911.

It is an arithmetic number, because the mean of its divisors is an integer number (10762120911).

Almost surely, 2^21524241821 is an apocalyptic number.

It is an amenable number.

21524241821 is a deficient number, since it is larger than the sum of its proper divisors (1).

21524241821 is an equidigital number, since it uses as much as digits as its factorization.

21524241821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10240, while the sum is 32.

The spelling of 21524241821 in words is "twenty-one billion, five hundred twenty-four million, two hundred forty-one thousand, eight hundred twenty-one".