21015241525 has 6 divisors (see below), whose sum is σ = 26058899522. Its totient is φ = 16812193200.

The previous prime is 21015241477. The next prime is 21015241531. The reversal of 21015241525 is 52514251012.

It can be written as a sum of positive squares in 3 ways, for example, as 4824969444 + 16190272081 = 69462^2 + 127241^2 .

It is not a de Polignac number, because 21015241525 - 2²⁷ = 20881023797 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21015241493 and 21015241502.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 420304806 + ... + 420304855.

Almost surely, 2^21015241525 is an apocalyptic number.

21015241525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21015241525 is a deficient number, since it is larger than the sum of its proper divisors (5043657997).

21015241525 is an equidigital number, since it uses as much as digits as its factorization.

21015241525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 840609671 (or 840609666 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 28.

Adding to 21015241525 its reverse (52514251012), we get a palindrome (73529492537).

The spelling of 21015241525 in words is "twenty-one billion, fifteen million, two hundred forty-one thousand, five hundred twenty-five".