123251209 has 4 divisors (see below), whose sum is σ = 124471620. Its totient is φ = 122030800.

The previous prime is 123251203. The next prime is 123251213. The reversal of 123251209 is 902152321.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 902152321 = 7 ⋅128878903.

It can be written as a sum of positive squares in 2 ways, for example, as 117505600 + 5745609 = 10840^2 + 2397^2 .

It is a cyclic number.

It is not a de Polignac number, because 123251209 - 2¹⁹ = 122726921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (123251203) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 610054 + ... + 610255.

It is an arithmetic number, because the mean of its divisors is an integer number (31117905).

Almost surely, 2^123251209 is an apocalyptic number.

It is an amenable number.

123251209 is a deficient number, since it is larger than the sum of its proper divisors (1220411).

123251209 is a wasteful number, since it uses less digits than its factorization.

123251209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1220410.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 123251209 is about 11101.8561060752. The cubic root of 123251209 is about 497.6573195055.

It can be divided in two parts, 1232 and 51209, that added together give a square (52441 = 229²).

The spelling of 123251209 in words is "one hundred twenty-three million, two hundred fifty-one thousand, two hundred nine".