21115211225 has 6 divisors (see below), whose sum is σ = 26182861950. Its totient is φ = 16892168960.

The previous prime is 21115211207. The next prime is 21115211317. The reversal of 21115211225 is 52211251112.

It can be written as a sum of positive squares in 3 ways, for example, as 16777216 + 21098434009 = 4096^2 + 145253^2 .

It is not a de Polignac number, because 21115211225 - 2⁸ = 21115210969 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21115211225.

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, 422304200 + ... + 422304249.

It is an arithmetic number, because the mean of its divisors is an integer number (4363810325).

Almost surely, 2^21115211225 is an apocalyptic number.

21115211225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21115211225 is a deficient number, since it is larger than the sum of its proper divisors (5067650725).

21115211225 is an equidigital number, since it uses as much as digits as its factorization.

21115211225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 844608459 (or 844608454 counting only the distinct ones).

The product of its digits is 400, while the sum is 23.

Adding to 21115211225 its reverse (52211251112), we get a palindrome (73326462337).

The spelling of 21115211225 in words is "twenty-one billion, one hundred fifteen million, two hundred eleven thousand, two hundred twenty-five".