1221661229 has 2 divisors, whose sum is σ = 1221661230. Its totient is φ = 1221661228.

The previous prime is 1221661219. The next prime is 1221661303. The reversal of 1221661229 is 9221661221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 985332100 + 236329129 = 31390^2 + 15373^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221661229 - 2¹⁶ = 1221595693 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1221661195 and 1221661204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221661219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610830614 + 610830615.

It is an arithmetic number, because the mean of its divisors is an integer number (610830615).

Almost surely, 2^1221661229 is an apocalyptic number.

It is an amenable number.

1221661229 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221661229 is an equidigital number, since it uses as much as digits as its factorization.

1221661229 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 32.

The square root of 1221661229 is about 34952.2707273791. The cubic root of 1221661229 is about 1069.0145026900.

The spelling of 1221661229 in words is "one billion, two hundred twenty-one million, six hundred sixty-one thousand, two hundred twenty-nine".