21243012125 has 16 divisors (see below), whose sum is σ = 26784606576. Its totient is φ = 16819200000.

The previous prime is 21243012103. The next prime is 21243012181. The reversal of 21243012125 is 52121034212.

It can be written as a sum of positive squares in 8 ways, for example, as 3653356249 + 17589655876 = 60443^2 + 132626^2 .

It is not a de Polignac number, because 21243012125 - 2⁸ = 21243011869 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21243012125.

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 15 ways as a sum of consecutive naturals, for example, 863876 + ... + 888125.

It is an arithmetic number, because the mean of its divisors is an integer number (1674037911).

Almost surely, 2^21243012125 is an apocalyptic number.

21243012125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21243012125 is a deficient number, since it is larger than the sum of its proper divisors (5541594451).

21243012125 is an equidigital number, since it uses as much as digits as its factorization.

21243012125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1752113 (or 1752103 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

Adding to 21243012125 its reverse (52121034212), we get a palindrome (73364046337).

The spelling of 21243012125 in words is "twenty-one billion, two hundred forty-three million, twelve thousand, one hundred twenty-five".