21005102225 has 12 divisors (see below), whose sum is σ = 26048265840. Its totient is φ = 16802830800.

The previous prime is 21005102221. The next prime is 21005102249. The reversal of 21005102225 is 52220150012.

It is a happy number.

It is not a de Polignac number, because 21005102225 - 2² = 21005102221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21005102197 and 21005102206.

It is not an unprimeable number, because it can be changed into a prime (21005102221) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 466766 + ... + 509784.

It is an arithmetic number, because the mean of its divisors is an integer number (2170688820).

Almost surely, 2^21005102225 is an apocalyptic number.

21005102225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21005102225 is a deficient number, since it is larger than the sum of its proper divisors (5043163615).

21005102225 is a wasteful number, since it uses less digits than its factorization.

21005102225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62560 (or 62555 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

Adding to 21005102225 its reverse (52220150012), we get a palindrome (73225252237).

The spelling of 21005102225 in words is "twenty-one billion, five million, one hundred two thousand, two hundred twenty-five".