123121309 has 2 divisors, whose sum is σ = 123121310. Its totient is φ = 123121308.

The previous prime is 123121307. The next prime is 123121333. The reversal of 123121309 is 903121321.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 92352100 + 30769209 = 9610^2 + 5547^2 .

It is a cyclic number.

It is not a de Polignac number, because 123121309 - 2¹ = 123121307 is a prime.

Together with 123121307, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 123121309.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (123121301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61560654 + 61560655.

It is an arithmetic number, because the mean of its divisors is an integer number (61560655).

Almost surely, 2^123121309 is an apocalyptic number.

It is an amenable number.

123121309 is a deficient number, since it is larger than the sum of its proper divisors (1).

123121309 is an equidigital number, since it uses as much as digits as its factorization.

123121309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 22.

The square root of 123121309 is about 11096.0041906986. The cubic root of 123121309 is about 497.4824235602.

The spelling of 123121309 in words is "one hundred twenty-three million, one hundred twenty-one thousand, three hundred nine".