1211221308025 has 27 divisors (see below), whose sum is σ = 1517347721421. Its totient is φ = 959120475840.

The previous prime is 1211221307993. The next prime is 1211221308107. The reversal of 1211221308025 is 5208031221121.

The square root of 1211221308025 is 1100555.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 517911954921 + 693309353104 = 719661^2 + 832652^2 .

It is not a de Polignac number, because 1211221308025 - 2⁵ = 1211221307993 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1211221307984 and 1211221308002.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 566784757 + ... + 566786893.

Almost surely, 2^{1211221308025} is an apocalyptic number.

1211221308025 is the 1100555-th square number.

1211221308025 is the 550278-th centered octagonal number.

It is an amenable number.

1211221308025 is a deficient number, since it is larger than the sum of its proper divisors (306126413396).

1211221308025 is an frugal number, since it uses more digits than its factorization.

1211221308025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4490 (or 2245 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 28.

Adding to 1211221308025 its reverse (5208031221121), we get a palindrome (6419252529146).

The spelling of 1211221308025 in words is "one trillion, two hundred eleven billion, two hundred twenty-one million, three hundred eight thousand, twenty-five".