1221385769 has 2 divisors, whose sum is σ = 1221385770. Its totient is φ = 1221385768.

The previous prime is 1221385747. The next prime is 1221385787. The reversal of 1221385769 is 9675831221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1220803600 + 582169 = 34940^2 + 763^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221385769 is a prime.

It is a super-2 number, since 2×1221385769² = 2983566393431442722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1221385069) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610692884 + 610692885.

It is an arithmetic number, because the mean of its divisors is an integer number (610692885).

Almost surely, 2^1221385769 is an apocalyptic number.

It is an amenable number.

1221385769 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221385769 is an equidigital number, since it uses as much as digits as its factorization.

1221385769 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 181440, while the sum is 44.

The square root of 1221385769 is about 34948.3299887133. The cubic root of 1221385769 is about 1068.9341495710.

The spelling of 1221385769 in words is "one billion, two hundred twenty-one million, three hundred eighty-five thousand, seven hundred sixty-nine".