21021355225 has 24 divisors (see below), whose sum is σ = 28082702592. Its totient is φ = 15517320000.

The previous prime is 21021355211. The next prime is 21021355247. The reversal of 21021355225 is 52255312012.

It is not a de Polignac number, because 21021355225 - 2¹³ = 21021347033 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21021355193 and 21021355202.

It is an unprimeable number.

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 in 23 ways as a sum of consecutive naturals, for example, 912600 + ... + 935350.

It is an arithmetic number, because the mean of its divisors is an integer number (1170112608).

Almost surely, 2^21021355225 is an apocalyptic number.

21021355225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21021355225 is a deficient number, since it is larger than the sum of its proper divisors (7061347367).

21021355225 is a wasteful number, since it uses less digits than its factorization.

21021355225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25617 (or 25612 counting only the distinct ones).

The product of its (nonzero) digits is 6000, while the sum is 28.

Adding to 21021355225 its reverse (52255312012), we get a palindrome (73276667237).

The spelling of 21021355225 in words is "twenty-one billion, twenty-one million, three hundred fifty-five thousand, two hundred twenty-five".