123129520 has 80 divisors (see below), whose sum is σ = 298552320. Its totient is φ = 47174400.

The previous prime is 123129509. The next prime is 123129527. The reversal of 123129520 is 25921321.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (123129527) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 324691 + ... + 325069.

It is an arithmetic number, because the mean of its divisors is an integer number (3731904).

Almost surely, 2^123129520 is an apocalyptic number.

123129520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 123129520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (149276160).

123129520 is an abundant number, since it is smaller than the sum of its proper divisors (175422800).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

123129520 is a wasteful number, since it uses less digits than its factorization.

123129520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 554 (or 548 counting only the distinct ones).

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

The square root of 123129520 is about 11096.3741825878. The cubic root of 123129520 is about 497.4934824024.

The spelling of 123129520 in words is "one hundred twenty-three million, one hundred twenty-nine thousand, five hundred twenty".