1312213821991 has 4 divisors (see below), whose sum is σ = 1313537953984. Its totient is φ = 1310889690000.

The previous prime is 1312213821829. The next prime is 1312213822009. The reversal of 1312213821991 is 1991283122131.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1312213821991 is a prime.

It is a super-2 number, since 2×1312213821991² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1312213821691) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 662064510 + ... + 662066491.

It is an arithmetic number, because the mean of its divisors is an integer number (328384488496).

Almost surely, 2^{1312213821991} is an apocalyptic number.

1312213821991 is a deficient number, since it is larger than the sum of its proper divisors (1324131993).

1312213821991 is an equidigital number, since it uses as much as digits as its factorization.

1312213821991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1324131992.

The product of its digits is 46656, while the sum is 43.

The spelling of 1312213821991 in words is "one trillion, three hundred twelve billion, two hundred thirteen million, eight hundred twenty-one thousand, nine hundred ninety-one".