1221401009 has 2 divisors, whose sum is σ = 1221401010. Its totient is φ = 1221401008.

The previous prime is 1221401003. The next prime is 1221401021. The reversal of 1221401009 is 9001041221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 632271025 + 589129984 = 25145^2 + 24272^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221401009 - 2²⁰ = 1220352433 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221401003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610700504 + 610700505.

It is an arithmetic number, because the mean of its divisors is an integer number (610700505).

Almost surely, 2^1221401009 is an apocalyptic number.

It is an amenable number.

1221401009 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221401009 is an equidigital number, since it uses as much as digits as its factorization.

1221401009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 1221401009 is about 34948.5480242027. The cubic root of 1221401009 is about 1068.9385954742.

The spelling of 1221401009 in words is "one billion, two hundred twenty-one million, four hundred one thousand, nine".