1221168747581 has 2 divisors, whose sum is σ = 1221168747582. Its totient is φ = 1221168747580.

The previous prime is 1221168747577. The next prime is 1221168747583. The reversal of 1221168747581 is 1857478611221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1056629805625 + 164538941956 = 1027925^2 + 405634^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221168747581 - 2² = 1221168747577 is a prime.

It is a super-2 number, since 2×1221168747581² (a number of 25 digits) contains 22 as substring.

Together with 1221168747583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221168747583) 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, 610584373790 + 610584373791.

It is an arithmetic number, because the mean of its divisors is an integer number (610584373791).

Almost surely, 2^{1221168747581} is an apocalyptic number.

It is an amenable number.

1221168747581 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221168747581 is an equidigital number, since it uses as much as digits as its factorization.

1221168747581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1505280, while the sum is 53.

The spelling of 1221168747581 in words is "one trillion, two hundred twenty-one billion, one hundred sixty-eight million, seven hundred forty-seven thousand, five hundred eighty-one".