123991812 has 144 divisors (see below), whose sum is σ = 384314112. Its totient is φ = 32901120.

The previous prime is 123991811. The next prime is 123991817. The reversal of 123991812 is 218199321.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (123991811) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 441112 + ... + 441392.

It is an arithmetic number, because the mean of its divisors is an integer number (2668848).

Almost surely, 2^123991812 is an apocalyptic number.

123991812 is a gapful number since it is divisible by the number (12) 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 123991812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (192157056).

123991812 is an abundant number, since it is smaller than the sum of its proper divisors (260322300).

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

123991812 is a wasteful number, since it uses less digits than its factorization.

123991812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 418 (or 413 counting only the distinct ones).

The product of its digits is 7776, while the sum is 36.

The square root of 123991812 is about 11135.1610675374. The cubic root of 123991812 is about 498.6521190322.

The spelling of 123991812 in words is "one hundred twenty-three million, nine hundred ninety-one thousand, eight hundred twelve".