1311221645 has 16 divisors (see below), whose sum is σ = 1667152368. Its totient is φ = 986603520.

The previous prime is 1311221629. The next prime is 1311221683. The reversal of 1311221645 is 5461221131.

It can be written as a sum of positive squares in 8 ways, for example, as 84400969 + 1226820676 = 9187^2 + 35026^2 .

It is not a de Polignac number, because 1311221645 - 2⁴ = 1311221629 is a prime.

It is a super-3 number, since 3×1311221645³ (a number of 28 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

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, 146705 + ... + 155385.

It is an arithmetic number, because the mean of its divisors is an integer number (104197023).

Almost surely, 2^1311221645 is an apocalyptic number.

It is an amenable number.

1311221645 is a deficient number, since it is larger than the sum of its proper divisors (355930723).

1311221645 is a wasteful number, since it uses less digits than its factorization.

1311221645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10480.

The product of its digits is 1440, while the sum is 26.

The square root of 1311221645 is about 36210.7945922207. The cubic root of 1311221645 is about 1094.5242040946.

Adding to 1311221645 its reverse (5461221131), we get a palindrome (6772442776).

The spelling of 1311221645 in words is "one billion, three hundred eleven million, two hundred twenty-one thousand, six hundred forty-five".