21421535225 has 6 divisors (see below), whose sum is σ = 26562703710. Its totient is φ = 17137228160.

The previous prime is 21421535209. The next prime is 21421535251. The reversal of 21421535225 is 52253512412.

It can be written as a sum of positive squares in 3 ways, for example, as 2288282896 + 19133252329 = 47836^2 + 138323^2 .

It is not a de Polignac number, because 21421535225 - 2⁴ = 21421535209 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21421535191 and 21421535200.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 428430680 + ... + 428430729.

It is an arithmetic number, because the mean of its divisors is an integer number (4427117285).

Almost surely, 2^21421535225 is an apocalyptic number.

21421535225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21421535225 is a deficient number, since it is larger than the sum of its proper divisors (5141168485).

21421535225 is an equidigital number, since it uses as much as digits as its factorization.

21421535225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 856861419 (or 856861414 counting only the distinct ones).

The product of its digits is 24000, while the sum is 32.

The spelling of 21421535225 in words is "twenty-one billion, four hundred twenty-one million, five hundred thirty-five thousand, two hundred twenty-five".