1221779931797 has 2 divisors, whose sum is σ = 1221779931798. Its totient is φ = 1221779931796.

The previous prime is 1221779931751. The next prime is 1221779931809. The reversal of 1221779931797 is 7971399771221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1184035601956 + 37744329841 = 1088134^2 + 194279^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221779931797 - 2²⁸ = 1221511496341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221779931737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610889965898 + 610889965899.

It is an arithmetic number, because the mean of its divisors is an integer number (610889965899).

Almost surely, 2^{1221779931797} is an apocalyptic number.

It is an amenable number.

1221779931797 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221779931797 is an equidigital number, since it uses as much as digits as its factorization.

1221779931797 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21003948, while the sum is 65.

The spelling of 1221779931797 in words is "one trillion, two hundred twenty-one billion, seven hundred seventy-nine million, nine hundred thirty-one thousand, seven hundred ninety-seven".