1211531031145 has 16 divisors (see below), whose sum is σ = 1513711397520. Its totient is φ = 930083788800.

The previous prime is 1211531031047. The next prime is 1211531031169. The reversal of 1211531031145 is 5411301351121.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 182318752144 + 1029212279001 = 426988^2 + 1014501^2 .

It is not a de Polignac number, because 1211531031145 - 2⁷ = 1211531031017 is a prime.

It is a super-2 number, since 2×1211531031145² (a number of 25 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48429360 + ... + 48454369.

It is an arithmetic number, because the mean of its divisors is an integer number (94606962345).

Almost surely, 2^{1211531031145} is an apocalyptic number.

It is an amenable number.

1211531031145 is a deficient number, since it is larger than the sum of its proper divisors (302180366375).

1211531031145 is an equidigital number, since it uses as much as digits as its factorization.

1211531031145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96883836.

The product of its (nonzero) digits is 1800, while the sum is 28.

Adding to 1211531031145 its reverse (5411301351121), we get a palindrome (6622832382266).

It can be divided in two parts, 12115 and 31031145, that added together give a triangular number (31043260 = T₇₈₇₉).

The spelling of 1211531031145 in words is "one trillion, two hundred eleven billion, five hundred thirty-one million, thirty-one thousand, one hundred forty-five".