123105709840 has 20 divisors (see below), whose sum is σ = 286220775564. Its totient is φ = 49242283904.

The previous prime is 123105709829. The next prime is 123105709843. The reversal of 123105709840 is 48907501321.

It can be written as a sum of positive squares in 2 ways, for example, as 81711365904 + 41394343936 = 285852^2 + 203456^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 123105709793 and 123105709802.

It is not an unprimeable number, because it can be changed into a prime (123105709843) 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, 769410607 + ... + 769410766.

Almost surely, 2^123105709840 is an apocalyptic number.

123105709840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

123105709840 is an abundant number, since it is smaller than the sum of its proper divisors (163115065724).

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

123105709840 is a wasteful number, since it uses less digits than its factorization.

123105709840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1538821386 (or 1538821380 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 40.

The spelling of 123105709840 in words is "one hundred twenty-three billion, one hundred five million, seven hundred nine thousand, eight hundred forty".