123209505 has 48 divisors (see below), whose sum is σ = 231154560. Its totient is φ = 62840448.

The previous prime is 123209503. The next prime is 123209533. The reversal of 123209505 is 505902321.

It is not a de Polignac number, because 123209505 - 2¹ = 123209503 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (123209501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 25741 + ... + 30149.

It is an arithmetic number, because the mean of its divisors is an integer number (4815720).

Almost surely, 2^123209505 is an apocalyptic number.

123209505 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

123209505 is a deficient number, since it is larger than the sum of its proper divisors (107945055).

123209505 is an equidigital number, since it uses as much as digits as its factorization.

123209505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4452 (or 4440 counting only the distinct ones).

The product of its (nonzero) digits is 2700, while the sum is 27.

The square root of 123209505 is about 11099.9777026803. The cubic root of 123209505 is about 497.6011830930.

It can be divided in two parts, 123 and 209505, that added together give a triangular number (209628 = T₆₄₇).

The spelling of 123209505 in words is "one hundred twenty-three million, two hundred nine thousand, five hundred five".