1221115409 has 2 divisors, whose sum is σ = 1221115410. Its totient is φ = 1221115408.

The previous prime is 1221115397. The next prime is 1221115411. The reversal of 1221115409 is 9045111221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1102240000 + 118875409 = 33200^2 + 10903^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221115409 - 2⁴ = 1221115393 is a prime.

It is a super-2 number, since 2×1221115409² = 2982245684194474562, which contains 22 as substring.

Together with 1221115411, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1221115459) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610557704 + 610557705.

It is an arithmetic number, because the mean of its divisors is an integer number (610557705).

Almost surely, 2^1221115409 is an apocalyptic number.

It is an amenable number.

1221115409 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221115409 is an equidigital number, since it uses as much as digits as its factorization.

1221115409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 1221115409 is about 34944.4617786567. The cubic root of 1221115409 is about 1068.8552723999.

The spelling of 1221115409 in words is "one billion, two hundred twenty-one million, one hundred fifteen thousand, four hundred nine".