1221511515225 has 24 divisors (see below), whose sum is σ = 2019600008160. Its totient is φ = 651461742720.

The previous prime is 1221511515209. The next prime is 1221511515233. The reversal of 1221511515225 is 5225151151221.

It is not a de Polignac number, because 1221511515225 - 2⁴ = 1221511515209 is a prime.

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, 6277597 + ... + 6469253.

It is an arithmetic number, because the mean of its divisors is an integer number (84150000340).

Almost surely, 2^{1221511515225} is an apocalyptic number.

1221511515225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1221511515225 is a deficient number, since it is larger than the sum of its proper divisors (798088492935).

1221511515225 is a wasteful number, since it uses less digits than its factorization.

1221511515225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276649 (or 276644 counting only the distinct ones).

The product of its digits is 10000, while the sum is 33.

Adding to 1221511515225 its reverse (5225151151221), we get a palindrome (6446662666446).

The spelling of 1221511515225 in words is "one trillion, two hundred twenty-one billion, five hundred eleven million, five hundred fifteen thousand, two hundred twenty-five".