1231216305 has 32 divisors (see below), whose sum is σ = 2218364928. Its totient is φ = 577694400.

The previous prime is 1231216303. The next prime is 1231216339. The reversal of 1231216305 is 5036121321.

It is not a de Polignac number, because 1231216305 - 2¹ = 1231216303 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1231216303) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 115239 + ... + 125468.

It is an arithmetic number, because the mean of its divisors is an integer number (69323904).

Almost surely, 2^1231216305 is an apocalyptic number.

1231216305 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1231216305 is a deficient number, since it is larger than the sum of its proper divisors (987148623).

1231216305 is a wasteful number, since it uses less digits than its factorization.

1231216305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240757.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 1231216305 is about 35088.6919818907. The cubic root of 1231216305 is about 1071.7943239038.

Adding to 1231216305 its reverse (5036121321), we get a palindrome (6267337626).

The spelling of 1231216305 in words is "one billion, two hundred thirty-one million, two hundred sixteen thousand, three hundred five".