1321011220391 has 2 divisors, whose sum is σ = 1321011220392. Its totient is φ = 1321011220390.

The previous prime is 1321011220387. The next prime is 1321011220423. The reversal of 1321011220391 is 1930221101231.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1321011220391 - 2² = 1321011220387 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1321011220391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1321011220691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660505610195 + 660505610196.

It is an arithmetic number, because the mean of its divisors is an integer number (660505610196).

Almost surely, 2^{1321011220391} is an apocalyptic number.

1321011220391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1321011220391 is an equidigital number, since it uses as much as digits as its factorization.

1321011220391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 26.

The spelling of 1321011220391 in words is "one trillion, three hundred twenty-one billion, eleven million, two hundred twenty thousand, three hundred ninety-one".