1221210989 has 2 divisors, whose sum is σ = 1221210990. Its totient is φ = 1221210988.

The previous prime is 1221210983. The next prime is 1221211021. The reversal of 1221210989 is 9890121221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 707826025 + 513384964 = 26605^2 + 22658^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221210989 - 2⁴ = 1221210973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221210983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610605494 + 610605495.

It is an arithmetic number, because the mean of its divisors is an integer number (610605495).

Almost surely, 2^1221210989 is an apocalyptic number.

It is an amenable number.

1221210989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221210989 is an equidigital number, since it uses as much as digits as its factorization.

1221210989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 35.

The square root of 1221210989 is about 34945.8293505820. The cubic root of 1221210989 is about 1068.8831590683.

The spelling of 1221210989 in words is "one billion, two hundred twenty-one million, two hundred ten thousand, nine hundred eighty-nine".