1220783561 has 2 divisors, whose sum is σ = 1220783562. Its totient is φ = 1220783560.

The previous prime is 1220783533. The next prime is 1220783579. The reversal of 1220783561 is 1653870221.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1170939961 + 49843600 = 34219^2 + 7060^2 .

It is an emirp because it is prime and its reverse (1653870221) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1220783561 is a prime.

It is not a weakly prime, because it can be changed into another prime (1220783591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610391780 + 610391781.

It is an arithmetic number, because the mean of its divisors is an integer number (610391781).

Almost surely, 2^1220783561 is an apocalyptic number.

It is an amenable number.

1220783561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1220783561 is an equidigital number, since it uses as much as digits as its factorization.

1220783561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 1220783561 is about 34939.7132358009. The cubic root of 1220783561 is about 1068.7584402694.

The spelling of 1220783561 in words is "one billion, two hundred twenty million, seven hundred eighty-three thousand, five hundred sixty-one".